18434( 2) - 11-Aug-2026 14:51:30 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 18434 Version: 2 Check-in Time: 11-Aug-2026 14:51:30 STScI Edit Number: 2 Title UV pulsations in accreting millisecond pulsars: a new window on the pulsar-disk interaction ------------------------------------------------------------------------------------ Type Cycle GO 34 ------------------------------------------------------------------------------------ Investigators Contact? PI: Dr. Giulia Illiano Institute of Space Sciences (ICE-CSIC) Y CoI: Dr. Arianna Miraval Zanon Agenzia Spaziale Italiana (ASI) Science N Data Center (ASDC) CoI: Francesco Coti Zelati Institute of Space Sciences (ICE-CSIC) N CoI: Dr. Alessio Marino Institute of Space Sciences (ICE-CSIC) N CoI: Dr. Alessandro Papitto INAF - Osservatorio Astronomico di Roma N CoI: Dr. Sergio Campana INAF - Osservatorio Astronomico di Brera N CoI: Dr. Maria Cristina Baglio INAF - Osservatorio Astronomico di Brera N CoI: Dr. Nanda Rea Institute of Space Sciences (ICE-CSIC) N CoI: Caterina Ballocco INAF - Osservatorio Astronomico di Roma N CoI: Dr. Filippo Ambrosino INAF - Osservatorio Astronomico di Roma N CoI: Dr. Riccardo La Placa INAF - Osservatorio Astronomico di Roma N CoI: Dr. Christian Malacaria INAF - Istituto Nazionale di Astrofisica N CoI: Dr. James Dennis Turner INAF - Osservatorio Astronomico di Roma N CoI: Dr. Domitilla De Martino Osservatorio Astronomico di Capodimonte N (OAC) CoI: Mr. Marco Maria Maria Messa INAF - Osservatorio Astronomico di Brera N ------------------------------------------------------------------------------------ Abstract Accreting millisecond pulsars (AMSPs) are the fastest-spinning neutron stars known, typically powered by mass transfer from a companion. However, the 2019 HST discovery of ultraviolet millisecond pulsations in SAX J1808.4-3658 challenged this paradigm, suggesting that magnetospheric particle acceleration can occur even during active accretion. The physical origin of these UV pulses remains one of the most intriguing mysteries in pulsar physics. We propose a disruptive Target of Opportunity program to observe one AMSP in outburst using the HST/STIS NUV-MAMA in TIME-TAG mode for 1 HST orbit. By timing UV pulsations across different accretion regimes, we aim to constrain the pulsar-disk interaction and the evolution of the emission mechanism during the outburst cycle. HST/STIS in TIME-TAG mode is the only facility capable of providing the temporal resolution and UV sensitivity required to resolve these signals, which are currently inaccessible from the ground or other space telescopes. To maximize the scientific return, each HST trigger will be supported by (quasi-)simultaneous X-ray monitoring with EP/FXT through pre-established collaboration. This synergy will provide the X-ray spectral context and the precise ephemeris required to fold the UV photons and search for coherent pulsations. ------------------------------------------------------------------------------------ Observations Description ------------------------ The unpredictable, short-lived nature of AMSP outbursts, which typically peak and decay within a few weeks (Di Salvo & Sanna 2022; Patruno & Watts 2021; Campana & Di Salvo 2018), poses a strict time-criticality requiring a 18434( 2) - 11-Aug-2026 14:51:30 - [ 2] disruptive ToO activation. While scientific success does not exclusively depend on catching the outburst peak (given that UV pulsations remain detectable during the decay phase (Ambrosino et al. 2021; Ballocco et al. 2026)) prompt execution is essential to capture the source in an accretion state before it inevitably returns to quiescence. We request the ToO observation to be performed using the STIS/NUV-MAMA detector in TIME-TAG mode (time resolution of 125 microseconds). This observation can only be carried out using instruments with a high temporal resolution (< 1 ms), capable of resolving millisecond pulsations in the UV band. There are no other instruments on ground-based telescopes suited to perform this type of UV-band study. STIS has successfully characterized fast variability in multiple fast pulsars (Sollerman et al. 2000; Romani et al. 2005; Shibanov et al. 2005; Mignani et al. 2019; Jaodand et al. 2021; Ambrosino et al. 2021; Miraval Zanon et al. 2022; Baglio et al. 2023; Ballocco et al. 2026). We request the G230L grating (1600-3100 A) with the 52x0.2 arcsec slit to ensure precise background subtraction for the pulsed component. We propose to observe 1 known or newly discovered AMSP in outburst for 1 HST orbit. Following guidance from the HST Help Desk, the APT uses a single generic "AMSP" placeholder. This entry covers all known AMSPs with confirmed optical counterparts and established ephemerides, as well as any new discoveries. The specific target will be selected at the time of the trigger based on the criteria described below. To assess the feasibility and ensure a conservative approach, we performed simulations using the STIS Exposure Time Calculator (ETC v. 34.1.1, STIS.sp.2327962), adopting the parameters of one of the most distant and faint AMSP, XTE J0929-314 (Giles et al. 2005). We assumed an average magnitude during the outburst of V = 18.8 mag, an extinction of E(B-V) = 0.2 mag, and a blackbody model with T = 15000 K to represent the disk contribution (see Supplementary Table 1 from Ambrosino et al. 2021). Our simulations show that with one orbit (~2700 s of net integration), we obtain a Signal-to-Noise Ratio (SNR) > 9 per resolution element at 2376 A. The total source counts integrated over the full NUV-MAMA bandpass exceed 6x10^4 photons. This photon statistics allow for a targeted single-trial search, exploiting the precise X-ray ephemeris from EP/FXT (obtained via priv. comm.), enabling the detection of millisecond pulsations with an amplitude as low as ~2% at a confidence level > 3sigma (Vaughan et al. 1994). This sensitivity threshold is well below the ~4% amplitude (~2.7% r.m.s.) estimated for SAX J1808.4-3658 (Ambrosino et al. 2021), ensuring that we can significantly detect UV pulsations even in the faintest AMSP with 1 HST orbit. To ensure the instrument safety according to the limits for irregularly variable sources (Table 7.8 from the STIS Instrument Handbook), we simulated an extremely bright AMSP at its outburst peak (V = 15 mag, E(B-V) = 0.1), with a T = 25000 K blackbody model to account for the maximum expected UV flux (STIS ETC v.32.2; STIS.sp.2320384). The global and peak local count rates are ~2953 counts/s and a ~1.1 counts/s/pixel, respectively, well below the required limits. ------------------------------------------------------------------------------------ 18434( 2) - 11-Aug-2026 14:51:30 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 2 SAX-J1808.4- STAR, BINARY PULSAR, RA=18H08M27.5800S, J2000 V = 17.6 3658 LMXB, NEUTRON STAR DEC=-36D58'43.90" Reference Frame: ICRS Comments: This object was generated by the targetselector and retrieved from the SIMBAD database. Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) 2000 0.0 0.0 0.0 ------------------------------------------------------------------------------------------------------------------------------------ 3 V-V1037-CAS STAR, BINARY PULSAR, RA=00H29M3.0600S, J2000 V = 17.4 LMXB, NEUTRON STAR DEC=+59D34'19.00" Reference Frame: ICRS Comments: This object was generated by the targetselector and retrieved from the SIMBAD database. Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) 2000 0.0 0.0 0.0 ------------------------------------------------------------------------------------------------------------------------------------ 4 V-BW-ANT STAR, BINARY PULSAR, RA=09H29M20.1900S, J2000 V = 18.8 LMXB, NEUTRON STAR DEC=-31D23'3.20" Reference Frame: ICRS Comments: This object was generated by the targetselector and retrieved from the SIMBAD database. Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) 2000 0.0 0.0 0.0 ------------------------------------------------------------------------------------------------------------------------------------ 5 V-V5511-SGR STAR, BINARY PULSAR, RA=18H13M39.0300S, J2000 V = 18.33 LMXB, NEUTRON STAR DEC=-33D46'22.30" Reference Frame: ICRS Comments: This object was generated by the targetselector and retrieved from the SIMBAD database. Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) 2000 0.0 0.0 0.0 ------------------------------------------------------------------------------------------------------------------------------------ 6 IGR-J17511-3 STAR, BINARY PULSAR, RA=17H51M8.5500S, J2000 V = 17 057 LMXB, NEUTRON STAR DEC=-30D57'41.70" Reference Frame: ICRS Comments: This object was generated by the targetselector and retrieved from the SIMBAD database. Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) 2000 0.0 0.0 0.0 ------------------------------------------------------------------------------------------------------------------------------------ 18434( 2) - 11-Aug-2026 14:51:30 - [ 4] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 7 2MAXI-J1900- STAR, BINARY PULSAR, RA=19H00M8.6500S, J2000 V = 18.09 248 LMXB, NEUTRON STAR DEC=-24D55'13.70" Reference Frame: ICRS Comments: This object was generated by the targetselector and retrieved from the SIMBAD database. Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) 2000 0.0 0.0 0.0 ------------------------------------------------------------------------------------------------------------------------------------ 8 KRL2007B-291 STAR, BINARY PULSAR, RA=17H51M13.4900S, J2000 V = 17.8 LMXB, NEUTRON STAR DEC=-30D37'23.40" Reference Frame: ICRS Comments: This object was generated by the targetselector and retrieved from the SIMBAD database. Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) 2000 0.0 0.0 0.0 ------------------------------------------------------------------------------------------------------------------------------------ 9 KRL2007B-304 STAR, BINARY PULSAR, RA=18H06M59.8000S, J2000 V = 18 LMXB, NEUTRON STAR DEC=-29D24'30.00" Reference Frame: ICRS Comments: This object was generated by the targetselector and retrieved from the SIMBAD database. Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) 2000 0.0 0.0 0.0 ------------------------------------------------------------------------------------------------------------------------------------ 10 IGR-J17494-3 STAR, BINARY PULSAR, RA=17H48M23.6200S, J2000 V = 17 030 LMXB, NEUTRON STAR DEC=-30D29'59.00" Reference Frame: ICRS Comments: This object was generated by the targetselector and retrieved from the SIMBAD database. Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) 2000 0.0 0.0 0.0 ------------------------------------------------------------------------------------------------------------------------------------ 11 XTE-J1737-37 STAR, BINARY PULSAR, RA=17H37M59.5000S, J2000 V = 16.8 6 LMXB, NEUTRON STAR DEC=-37D46'20.00" Reference Frame: ICRS Comments: This object was generated by the targetselector and retrieved from the SIMBAD database. Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) 2000 0.0 0.0 0.0 ------------------------------------------------------------------------------------------------------------------------------------ 18434( 2) - 11-Aug-2026 14:51:30 - [ 5] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 12 IGR-J18245-2 STAR, BINARY PULSAR, RA=18H24M32.5000S, J2000 V = 17.5 452 LMXB, NEUTRON STAR DEC=-24D52'7.80" Reference Frame: ICRS Comments: This object was generated by the targetselector and retrieved from the SIMBAD database. Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) 2000 0.0 0.0 0.0 ------------------------------------------------------------------------------------------------------------------------------------ 18434( 2) - 11-Aug-2026 14:51:30 - [ 6] TARGET LIST Generic Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Selection Criteria | Flux data No | Name | Description | | ------------------------------------------------------------------------------------------------------------------------------------ 1 GENERIC-AMSP STAR, BINARY PULSAR, SEE COMMENTS V = 15 +/- 19 LMXB, NEUTRON STAR Comments: The target will be a known or newly discovered accreting millisecond pulsar (AMSP) in outburst, satisfying all of the following conditions at the time of trigger: Classification and ephemeris: The source is confirmed to be an AMSP in outburst via X-ray monitoring (EP/WXT, MAXI) or optical monitoring (LCO). For newly discovered transients, EP/FXT observations establish the AMSP nature and provide the timing ephemeris. For known sources, existing timing solutions are updated via EP/FXT as needed. Flux and extinction: The source has a detected optical counterpart and NH < 4x10^21 cm^-2 (E(B-V) < 0.6 mag). The 0.5-10 keV X-ray flux is FX >= 10^-10 erg cm^-2 s^-1 (LX ~ 8x10^35 erg s^-1 at 8 kpc), ensuring a representative outburst state. Visibility: The source is visible to HST (verified in APT) and satisfies all scheduling constraints (e.g., no solar constraints) at the time of the trigger. The specific target is selected from the list of known AMSPs included in this proposal, or corresponds to a newly discovered AMSP meeting the above criteria, whichever occurs first and is confirmed by our EP/FXT and LCO collaboration. ------------------------------------------------------------------------------------------------------------------------------------ 18434( 2) - 11-Aug-2026 14:51:30 - [ 7] Visit: 01 Visit Requirements: TOO MIN RESPONSE TIME 2.0D; TOO MAX RESPONSE TIME 14.0D On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 SAX-J1808.4 STIS/CCD ACQ F28X50LP MIRROR 1 5 S (5 S) -3658 ------------------------------------------------------------------------------------------------------------------------------------ 2 SAX-J1808.4 STIS/NUV TIME-TA 52X0.2 G230L 2376 BUFFER-TIME=600 1 2000 S -3658 -MAMA G (2000 S) ------------------------------------------------------------------------------------------------------------------------------------ Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ SAX-J1808.4-3658 1 STIS/CCD ACQ F28X50LP MIRROR none none none none 1 N/A SAX-J1808.4-3658 2 STIS/NUV TIME-TA 52X0.2 G230L 2376 none none none none 1 N/A -MAMA G 18434( 2) - 11-Aug-2026 14:51:30 - [ 8] Visit: 02 Visit Requirements: TOO MIN RESPONSE TIME 2.0D; TOO MAX RESPONSE TIME 14.0D On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 V-V1037-CAS STIS/CCD ACQ F28X50LP MIRROR 1 4 S (4 S) ------------------------------------------------------------------------------------------------------------------------------------ 2 V-V1037-CAS STIS/NUV TIME-TA 52X0.2 G230L 2376 BUFFER-TIME=600 1 2000 S -MAMA G (2000 S) ------------------------------------------------------------------------------------------------------------------------------------ Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ V-V1037-CAS 1 STIS/CCD ACQ F28X50LP MIRROR none none none none 1 N/A V-V1037-CAS 2 STIS/NUV TIME-TA 52X0.2 G230L 2376 none none none none 1 N/A -MAMA G 18434( 2) - 11-Aug-2026 14:51:30 - [ 9] Visit: 03 Visit Requirements: TOO MIN RESPONSE TIME 2.0D; TOO MAX RESPONSE TIME 14.0D On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 V-BW-ANT STIS/CCD ACQ F28X50LP MIRROR 1 14 S (14 S) ------------------------------------------------------------------------------------------------------------------------------------ 2 V-BW-ANT STIS/NUV TIME-TA 52X0.2 G230L 2376 BUFFER-TIME=600 1 2000 S -MAMA G (2000 S) ------------------------------------------------------------------------------------------------------------------------------------ Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ V-BW-ANT 1 STIS/CCD ACQ F28X50LP MIRROR none none none none 1 N/A V-BW-ANT 2 STIS/NUV TIME-TA 52X0.2 G230L 2376 none none none none 1 N/A -MAMA G 18434( 2) - 11-Aug-2026 14:51:30 - [ 10] Visit: 04 Visit Requirements: TOO MIN RESPONSE TIME 2.0D; TOO MAX RESPONSE TIME 14.0D On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 V-V5511-SGR STIS/CCD ACQ F28X50LP MIRROR 1 9 S (9 S) ------------------------------------------------------------------------------------------------------------------------------------ 2 V-V5511-SGR STIS/NUV TIME-TA 52X0.2 G230L 2376 BUFFER-TIME=600 1 2000 S -MAMA G (2000 S) ------------------------------------------------------------------------------------------------------------------------------------ Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ V-V5511-SGR 1 STIS/CCD ACQ F28X50LP MIRROR none none none none 1 N/A V-V5511-SGR 2 STIS/NUV TIME-TA 52X0.2 G230L 2376 none none none none 1 N/A -MAMA G 18434( 2) - 11-Aug-2026 14:51:30 - [ 11] Visit: 05 Visit Requirements: TOO MIN RESPONSE TIME 2.0D; TOO MAX RESPONSE TIME 14.0D On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 IGR-J17511- STIS/CCD ACQ F28X50LP MIRROR 1 3 S (3 S) 3057 ------------------------------------------------------------------------------------------------------------------------------------ 2 IGR-J17511- STIS/NUV TIME-TA 52X0.2 G230L 2376 BUFFER-TIME=600 1 2000 S 3057 -MAMA G (2000 S) ------------------------------------------------------------------------------------------------------------------------------------ Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ IGR-J17511-3057 1 STIS/CCD ACQ F28X50LP MIRROR none none none none 1 N/A IGR-J17511-3057 2 STIS/NUV TIME-TA 52X0.2 G230L 2376 none none none none 1 N/A -MAMA G 18434( 2) - 11-Aug-2026 14:51:30 - [ 12] Visit: 06 Visit Requirements: TOO MIN RESPONSE TIME 2.0D; TOO MAX RESPONSE TIME 14.0D On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 2MAXI-J1900 STIS/CCD ACQ F28X50LP MIRROR 1 7 S (7 S) -248 ------------------------------------------------------------------------------------------------------------------------------------ 2 2MAXI-J1900 STIS/NUV TIME-TA 52X0.2 G230L 2376 BUFFER-TIME=600 1 2000 S -248 -MAMA G (2000 S) ------------------------------------------------------------------------------------------------------------------------------------ Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ 2MAXI-J1900-248 1 STIS/CCD ACQ F28X50LP MIRROR none none none none 1 N/A 2MAXI-J1900-248 2 STIS/NUV TIME-TA 52X0.2 G230L 2376 none none none none 1 N/A -MAMA G 18434( 2) - 11-Aug-2026 14:51:30 - [ 13] Visit: 07 Visit Requirements: TOO MIN RESPONSE TIME 2.0D; TOO MAX RESPONSE TIME 14.0D On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 KRL2007B-29 STIS/CCD ACQ F28X50LP MIRROR 1 6 S (6 S) 1 ------------------------------------------------------------------------------------------------------------------------------------ 2 KRL2007B-29 STIS/NUV TIME-TA 52X0.2 G230L 2376 BUFFER-TIME=600 1 2000 S 1 -MAMA G (2000 S) ------------------------------------------------------------------------------------------------------------------------------------ Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ KRL2007B-291 1 STIS/CCD ACQ F28X50LP MIRROR none none none none 1 N/A KRL2007B-291 2 STIS/NUV TIME-TA 52X0.2 G230L 2376 none none none none 1 N/A -MAMA G 18434( 2) - 11-Aug-2026 14:51:30 - [ 14] Visit: 08 Visit Requirements: TOO MIN RESPONSE TIME 2.0D; TOO MAX RESPONSE TIME 14.0D On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 KRL2007B-30 STIS/CCD ACQ F28X50LP MIRROR 1 7 S (7 S) 4 ------------------------------------------------------------------------------------------------------------------------------------ 2 KRL2007B-30 STIS/NUV TIME-TA 52X0.2 G230L 2376 BUFFER-TIME=600 1 2000 S 4 -MAMA G (2000 S) ------------------------------------------------------------------------------------------------------------------------------------ Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ KRL2007B-304 1 STIS/CCD ACQ F28X50LP MIRROR none none none none 1 N/A KRL2007B-304 2 STIS/NUV TIME-TA 52X0.2 G230L 2376 none none none none 1 N/A -MAMA G 18434( 2) - 11-Aug-2026 14:51:30 - [ 15] Visit: 09 Visit Requirements: TOO MIN RESPONSE TIME 2.0D; TOO MAX RESPONSE TIME 14.0D On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 IGR-J17494- STIS/CCD ACQ F28X50LP MIRROR 1 3 S (3 S) 3030 ------------------------------------------------------------------------------------------------------------------------------------ 2 IGR-J17494- STIS/NUV TIME-TA 52X0.2 G230L 2376 BUFFER-TIME=600 1 2000 S 3030 -MAMA G (2000 S) ------------------------------------------------------------------------------------------------------------------------------------ Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ IGR-J17494-3030 1 STIS/CCD ACQ F28X50LP MIRROR none none none none 1 N/A IGR-J17494-3030 2 STIS/NUV TIME-TA 52X0.2 G230L 2376 none none none none 1 N/A -MAMA G 18434( 2) - 11-Aug-2026 14:51:30 - [ 16] Visit: 10 Visit Requirements: TOO MIN RESPONSE TIME 2.0D; TOO MAX RESPONSE TIME 14.0D On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 XTE-J1737-3 STIS/CCD ACQ F28X50LP MIRROR 1 3 S (3 S) 76 ------------------------------------------------------------------------------------------------------------------------------------ 2 XTE-J1737-3 STIS/NUV TIME-TA 52X0.2 G230L 2376 BUFFER-TIME=600 1 2000 S 76 -MAMA G (2000 S) ------------------------------------------------------------------------------------------------------------------------------------ Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ XTE-J1737-376 1 STIS/CCD ACQ F28X50LP MIRROR none none none none 1 N/A XTE-J1737-376 2 STIS/NUV TIME-TA 52X0.2 G230L 2376 none none none none 1 N/A -MAMA G 18434( 2) - 11-Aug-2026 14:51:30 - [ 17] Visit: 11 Visit Requirements: TOO MIN RESPONSE TIME 2.0D; TOO MAX RESPONSE TIME 14.0D On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 IGR-J18245- STIS/CCD ACQ F28X50LP MIRROR 1 4 S (4 S) 2452 ------------------------------------------------------------------------------------------------------------------------------------ 2 IGR-J18245- STIS/NUV TIME-TA 52X0.2 G230L 2376 BUFFER-TIME=600 1 2000 S 2452 -MAMA G (2000 S) ------------------------------------------------------------------------------------------------------------------------------------ Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ IGR-J18245-2452 1 STIS/CCD ACQ F28X50LP MIRROR none none none none 1 N/A IGR-J18245-2452 2 STIS/NUV TIME-TA 52X0.2 G230L 2376 none none none none 1 N/A -MAMA G 18434( 2) - 11-Aug-2026 14:51:30 - [ 18] Visit: 12 Visit Requirements: TOO MIN RESPONSE TIME 2.0D; TOO MAX RESPONSE TIME 14.0D On Hold Comments: Additional Comments: Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ 1 GENERIC-AMS STIS/CCD ACQ F28X50LP MIRROR 1 41 S (41 P S) ------------------------------------------------------------------------------------------------------------------------------------ 2 GENERIC-AMS STIS/NUV TIME-TA 52X0.2 G230L 2376 BUFFER-TIME=600 1 1900 S P -MAMA G (1900 S) ------------------------------------------------------------------------------------------------------------------------------------ Sub Exposures ------------------------------------------------------------------------------------------------------------------------------------ Target | Exp |Instr | Oper. | Aper |Spectral|Cent.|Primary |Secondary |Iteration |CR-SPLIT |Orbit |Duration Name | Num |Config | Mode | or FOV |Element |Wave.|Pattern Pos |Pattern Pos |Num |Num |Number | ------------------------------------------------------------------------------------------------------------------------------------ GENERIC-AMSP 1 STIS/CCD ACQ F28X50LP MIRROR none none none none 1 N/A GENERIC-AMSP 2 STIS/NUV TIME-TA 52X0.2 G230L 2376 none none none none 1 N/A -MAMA G 18434( 2) - 11-Aug-2026 14:51:30 - [ 19] Summary Form for Proposal 18434 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures 52X0.2, F28X50LP ------------------------------------------------------------------------------------------------------------------------------------ Configurations STIS/CCD, STIS/NUV-MAMA ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACQ, TIME-TAG ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters BUFFER-TIME=600 ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements TOO MAX RESPONSE TIME 14.0D, TOO MIN RESPONSE TIME 2.0D ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements G230L, MIRROR ------------------------------------------------------------------------------------------------------------------------------------ Target Names 2MAXI-J1900-248, GENERIC-AMSP, IGR-J17494-3030, IGR-J17511-3057, IGR-J18245-2452, KRL2007B-291, KRL2007B-304, SAX-J1808.4-3658, V-BW-ANT, V-V1037-CAS, V-V5511-SGR, XTE-J1737-376 ------------------------------------------------------------------------------------------------------------------------------------