17900( 4) - 13-Mar-2025 18:25:35 - [ 1] HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 17900 Version: 4 Check-in Time: 13-Mar-2025 18:25:35 STScI Edit Number: 0 Title Exploring dust in the star forming region towards Cyg X-1 ------------------------------------------------------------------------------------ Type Cycle GO 32 ------------------------------------------------------------------------------------ Investigators Contact? PI: Dr. Elisa Costantini Space Research Organization Netherlands Y CoI: Dr. Sascha Zeegers European Space Agency - ESTEC N CoI: Dr. Ioanna Psaradaki Massachusetts Institute of Technology N CoI: Dr. Missagh Mehdipour Space Telescope Science Institute N CoI: Dr. Daniele Rogantini University of Chicago N CoI: Dr. Gilles P.P.L. Otten Academia Sinica, Institute of Astronomy N and Astrophysics ------------------------------------------------------------------------------------ Abstract Cyg X-1 is a bright nearby source, located in a complex dusty region. Its dust grains and gas characteristics differ from the average of the diffuse medium, providing unique insights into dust in a star and planets forming site. Using the high-resolution of XMMNewton-RGS we will characterise the chemistry, size and abundance of interstellar dust around the oxygen spectral region, fundamental to determine the silicate contribution to the dust composition. Using the joint HST-STIS observation we will model the extinction curve and carbon features, giving unique insight on the dust size distribution and carbon content along this line of sight. ------------------------------------------------------------------------------------ Observations Description ------------------------ Note: this HST observation is a joint observation via an XMM-Newton proposal. The HST observation does not need to be strictly simultaneous with the XMM observation. A reaction time of 1 week has been proposed, however a longer response time is also doable without loss of science information. A longer response time may be in fact necessary as the visibility windows of HST and XMM do not perfectly overlap. If the XMM observation is triggered when there is no HST window available, it is fine if the target is observed by HST at the next possible occasion (1-3 months away, depending on when this happens during the cycle). In the proposal we indicated 1 HST orbit, using G430L, G750L and G230L. However, the U band=9.38, is too bright for G230L (as written in the proposal). This will cause the G230L to saturate and instead we need to use E230M. For G430L and G750L we take 10 second exposures at 3 nod positions along the slit (nods needed to fully sample spectrum). SNR here is 200+ per exposure at R=500. Finally, we take CCDFLATs in occultation time to allow correcting of detector fringing. 17900( 4) - 13-Mar-2025 18:25:35 - [ 2] For the E230M the central wavelength 2415 A covers 1985 A to 2820 A which includes the 2175 A absorption feature and adjacent continuum. At the deepest part of the feature (2175A) the SNR is 2.8 per resolution element (R=30000). Binning to R=500 gives SNR 21 per exposure. Two exposures will be collected with MAMA (two iterations without nodding) so the SNR will be even higher. Acquisition will take place with neutral density filter to avoid saturation. Bright Object Limit has been verified with archival SWIFT UVOT photometry. Renormalizing our reddened O9V star model with these photometric points remains safely within the Bright Object Limits for MAMA, even with the brightest observed photometry in Cyg X-1's high-state (0.051 Jy at 2246 Angstrom; https://etc.stsci.edu/etc/results/STIS.sp.1952842/). ------------------------------------------------------------------------------------ 17900( 4) - 13-Mar-2025 18:25:35 - [ 3] TARGET LIST Fixed Targets ------------------------------------------------------------------------------------------------------------------------------------ Tar| Target | Target | Target |Coord | Radial | Flux data No | Name | Description | Position |Eqnx | Vel. | ------------------------------------------------------------------------------------------------------------------------------------ 1 HD-226868 STAR, LMXB RA=19H58M21.6757S, J2000 V = V = 8.91 U band=9.38 DEC=+35D12'5.78" -2.70 Reference Frame: ICRS Extended: NO Comments: This object was generated by the targetselector and retrieved from the SIMBAD database. SIMBAD listed proper motion for this target. When retrieving targets with PM from SIMBAD, APT requests the coordinates be calculated with an epoch of the year 2000. Do not modify this epoch. Always review coordinates using the Target Confirmation tool, which graphically displays the PM. Epoch of Position RA proper motion (seconds of time/yr) DEC Proper Motion (arcsec/yr) Annual Parallax (arcsec) 2000 -3.110077021018445E-4 -0.006310000048870279 4.439E-4 ------------------------------------------------------------------------------------------------------------------------------------ 17900( 4) - 13-Mar-2025 18:25:35 - [ 4] Patterns ------------------------------------------------------------------------------------------------------------------------------------ Pattern_Number: 1 Primary_Pattern Secondary_Pattern Pattern_Type STIS-ALONG-SLIT Pattern_Purpose DITHER Number_Of_Points 3 Point_Spacing 0.5327175 Line_Spacing Coordinate_Frame POS-TARG Pattern_Orient 90.0 Angle_Between_Sides Center_Pattern NO Pattern_Comments: CCD nodding pattern with 3 positions, each step equivalent to 10.5 pixels which allows improving spectral resolution, preventing aliasing from undersampling and reduced impact of detector artefacts. ------------------------------------------------------------------------------------------------------------------------------------ 17900( 4) - 13-Mar-2025 18:25:35 - [ 5] Visit: 01 (Cyg X-1) Visit Requirements: TOO RESPONSE TIME 7.0D 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 HD-226868 STIS/CCD ACQ F25ND3 MIRROR 1 1 S (1 S) Comments: Note that we are close to saturation on the acquisition with default aperture F28X50LP (t_sat = 0.14 sec and minimum exposure time 0.1 sec). So we use aperture F25ND3 with 1 second integration and S/N = 88 to be on the safe side. ------------------------------------------------------------------------------------------------------------------------------------ 2 HD-226868 STIS/NUV ACCUM 0.2X0.2 E230M 2415 2 223 S (446 -MAMA S) Comments: MAMA saturates in G230L (this grating was originally suggested in the proposal). For this target MAMA can only be used with the high and medium res echelles without having to resort to the ND gratings to prevent saturation in the worst case (brightest) scenarios. The CCD with G230LB would create issues with scattered light from the red end of the spectrum. We don't need the full spectral resolution so we can use 6x0.2 or 0.2x0.2 apertures. Aperture 0.2x0.2 minimizes order-order contamination. We do not need to PEAKUP with these apertures which saves a lot of time. SNR = 10.5 per resolution element per 223s integration time per pointing at 2500A. SNR = 2.8 (per resolution element) at 2175 A (STIS.sp.1952839). Double the amount of integration time in the two iterations. We can only fit one wavelength setting in this orbit. So we pick 2415A which covers 2175 A and the adjacent continuum (1985 A to 2820 A). Worst case (brightest flux in UV from SWIFT UVOT): https://etc.stsci.edu/etc/results/STIS.sp.195 2842/ is still within safe limits. 17900( 4) - 13-Mar-2025 18:25:35 - [ 6] Exposures ------------------------------------------------------------------------------------------------------------------------------------ Exp | Target | Instr | Oper. | Aper |Spectral|Central| Optional |Num| Time | Special Num | Name | Config | Mode | or FOV |Element |Waveln.| Parameters |Exp| (Total) | Requirements ------------------------------------------------------------------------------------------------------------------------------------ ------------------------------------------------------------------------------------------------------------------------------------ 3 HD-226868 STIS/CCD ACCUM 52X2 G430L 4300 CR-SPLIT=2 1 10 S (30 PATTERN 1 3 S) Comments: SNR 192 per 10 second pattern position. With 3 pointings in this pattern we have 30 seconds integration. CR-SPLIT = 2 (default) provides some safety against cosmic ray hits. ------------------------------------------------------------------------------------------------------------------------------------ 4 HD-226868 STIS/CCD ACCUM 52X2 G750L 7751 CR-SPLIT=2 1 10 S (30 PATTERN 1 4 S) Comments: SNR 270 per 10 second pattern position. Total integration time 30 seconds. ------------------------------------------------------------------------------------------------------------------------------------ 5 CCDFLAT STIS/CCD ACCUM 52X0.1 G750L 7751 2 DEF (0 S) Comments: CCDFLAT is needed to correct for fringes in the reddest part of G750L and taken during the occultation time with default integration times. A reduced slit width of 52x0.1 is used to be more like a point source. It is unclear if a square aperture would yield even better fringe correction. ------------------------------------------------------------------------------------------------------------------------------------ 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 | ------------------------------------------------------------------------------------------------------------------------------------ HD-226868 1 STIS/CCD ACQ F25ND3 MIRROR none none none none 1 N/A HD-226868 2 STIS/NUV ACCUM 0.2X0.2 E230M 2415 none none 1 none 1 N/A -MAMA HD-226868 2 STIS/NUV ACCUM 0.2X0.2 E230M 2415 none none 2 none 1 N/A -MAMA HD-226868 3 STIS/CCD ACCUM 52X2 G430L 4300 1 none none 1 1 N/A HD-226868 3 STIS/CCD ACCUM 52X2 G430L 4300 1 none none 2 1 N/A HD-226868 3 STIS/CCD ACCUM 52X2 G430L 4300 2 none none 1 1 N/A HD-226868 3 STIS/CCD ACCUM 52X2 G430L 4300 2 none none 2 1 N/A HD-226868 3 STIS/CCD ACCUM 52X2 G430L 4300 3 none none 1 1 N/A HD-226868 3 STIS/CCD ACCUM 52X2 G430L 4300 3 none none 2 1 N/A HD-226868 4 STIS/CCD ACCUM 52X2 G750L 7751 1 none none 1 1 N/A HD-226868 4 STIS/CCD ACCUM 52X2 G750L 7751 1 none none 2 1 N/A HD-226868 4 STIS/CCD ACCUM 52X2 G750L 7751 2 none none 1 1 N/A HD-226868 4 STIS/CCD ACCUM 52X2 G750L 7751 2 none none 2 1 N/A HD-226868 4 STIS/CCD ACCUM 52X2 G750L 7751 3 none none 1 1 N/A HD-226868 4 STIS/CCD ACCUM 52X2 G750L 7751 3 none none 2 1 N/A CCDFLAT 5 STIS/CCD ACCUM 52X0.1 G750L 7751 none none 1 none 1 N/A CCDFLAT 5 STIS/CCD ACCUM 52X0.1 G750L 7751 none none 2 none 1 N/A 17900( 4) - 13-Mar-2025 18:25:35 - [ 7] Summary Form for Proposal 17900 Item Used in this proposal ------------------------------------------------------------------------------------------------------------------------------------ Apertures 0.2X0.2, 52X0.1, 52X2, F25ND3 ------------------------------------------------------------------------------------------------------------------------------------ Configurations STIS/CCD, STIS/NUV-MAMA ------------------------------------------------------------------------------------------------------------------------------------ Opmodes ACCUM, ACQ ------------------------------------------------------------------------------------------------------------------------------------ Optional Parameters CR-SPLIT=2 ------------------------------------------------------------------------------------------------------------------------------------ Special Requirements PATTERN 1 3, PATTERN 1 4, TOO RESPONSE TIME 7.0D ------------------------------------------------------------------------------------------------------------------------------------ Spectral Elements E230M, G430L, G750L, MIRROR ------------------------------------------------------------------------------------------------------------------------------------ Target Names CCDFLAT, HD-226868 ------------------------------------------------------------------------------------------------------------------------------------