0 Assigned ID: 3858 ----- Attempting Submission 1 (Fri Oct 21 22:35:04 GMT 2022) ----- I have updated the pos targ values to 1arcsec to account for self persistence. 676107368 ----- Attempting Submission 1 (Fri Oct 28 13:11:00 GMT 2022) ----- HST Phase II Proposal 17263 successfully submitted. Receipt: # 17263-1 ----- Attempting Submission 2 (Fri Oct 28 16:27:47 GMT 2022) ----- Catching the accretion burst of a massive protostar on the rise with the HST A wealth of new theoretical and observational evidence supports now the idea that episodic accretion is a fundamental and common phenomenon across mass and time in star formation. In particular, the most recent discovery and follow-up of three accretion bursts from high mass young stellar objects (HMYSOs) have been key to link low- and high-mass star-formation mechanisms to the common ground of disk-mediated accretion. Among those, only one (S255IR NIRS 3) could be detected and studied at NIR wavelengths, just after the burst maximum. A new accretion burst from Mol77, a 10 Msun protostar, begun in the first week of October 2022. This provides us with the unique chance to study such rare events from an early stage. We request HST/WFC3 observations to map the source and its outflow cavity to confirm the burst in the infrared. We will also derive the pre-burst spectrum of Mol77, as the cavity walls still see the pre-outburst phase. Finally, we will for the first time measure the light echo with the HST for a HMYSO. This program will observe the outbursting high-mass young stellar object Mol77 in two epochs. We aim at observing the ligh echo from the burst and therefore we want the two epochs as separated as possible within the observability window. Each epoch will be observed with one orbit. Therefore the total length of the programme is two orbits. Each orbit will observe four filters, namely F110W and F160W for broad-band filters and F128N and F164N for narrow-band filters. Dr. Ruben Fedriani is an expert in NIR observational studies, in particular in the study of high-mass star formation. He has led previous publications using HST data. He is PI of HST proposals. Dr. Alessio Caratti o Garatti is an expert in observational studies of low- and high-mass star formation with ground, airborne, and space based IR facilities. He has led the first outburst study of S255. Dr. Fabrizio Massi is an expert in optical and near-infrared observations and he has led previous pubications on protostellar outflows. Dr. Riccardo Cesaroni is an expert in massive star formation and has led the radio follow-up of S255. Dr. Jochen Eisloffel is an expert in star formation studies and protostellar outflows studies. Dr. Bringfried Stecklum is an expert in massive star formation and has led the study of the outbursting HMYSO G358. Stellar Populations and the Interstellar Medium 6 false SUPPORTED STAR EJECTA JET KNOT PRE-MAIN SEQUENCE STAR YSO YES The NIR counterpart source is 2MASS 18551666+0305079 J2000 J2000 J=15.8;H=14 WFC3/IR Imaging No No F110W WFC3/IR Imaging No No F128N WFC3/IR Imaging No No F160W WFC3/IR Imaging No No F164N WFC3/IR Imaging No No F110W WFC3/IR Imaging No No F128N WFC3/IR Imaging No No F160W WFC3/IR Imaging No No F164N WFC3/IR Imaging No No F110W WFC3/IR Imaging No No F128N WFC3/IR Imaging No No F160W WFC3/IR Imaging No No F164N The scheduling data was generated by CASM 30.3. CASM was run in Phase II mode. This is the first epoch of the programme and should be executed as soon as possible 1667774231000 70.4818029183705 (Tic-Visit :proposal-id 17263 :visit-id "01" :proposal-version -1 :trans-version "20220516" :date "28-Oct-2022 18:24:36.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "30" :si-bright-earth-limb-angle 20.0 :data-volume 1758288 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 17263 :visit-id "01" :obset-id "01" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 17263 :visit-id "01" :orbit-number 1 :pcs-time 383 :si-vis-utilization 2723 :al-overhead-at-end 0 :internal-dur-at-end 633 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3142 :pcs-gap 0 ) true 1 0 This is the first epoch of the programme and should be executed as soon as possible HOPR repeat of visit 01. (Tic-Visit :proposal-id 17263 :visit-id "01" :proposal-version -1 :trans-version "20220516" :date "28-Oct-2022 18:24:36.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "30" :si-bright-earth-limb-angle 20.0 :data-volume 1758288 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 17263 :visit-id "01" :obset-id "01" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 17263 :visit-id "01" :orbit-number 1 :pcs-time 383 :si-vis-utilization 2723 :al-overhead-at-end 0 :internal-dur-at-end 633 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3142 :pcs-gap 0 ) false 1 0 The scheduling data was generated by CASM 30.3. CASM was run in Phase II mode. This is the second epoch of the programme and should be executed as far apart as possible with respecto to the epoch one (visit 01) 1668653897000 64.50112480460061 (Tic-Visit :proposal-id 17263 :visit-id "02" :proposal-version -1 :trans-version "20220516" :date "28-Oct-2022 18:24:37.0" :trans-errors '(:WARNINGS 0 :ERRORS 0 :HEALTH-AND-SAFETY 0 :FATAL-ERRORS 0 :CONTINUABLE-FATALS 0) :number-of-orbits 1 :saa-model "30" :si-bright-earth-limb-angle 20.0 :data-volume 1758288 :tdrss-contact-duration 0 :coron NIL ) (Tic-Obset :proposal-id 17263 :visit-id "02" :obset-id "02" :pcs-mode "FGS" ) (Tic-Orbit :proposal-id 17263 :visit-id "02" :orbit-number 1 :pcs-time 383 :si-vis-utilization 2723 :al-overhead-at-end 0 :internal-dur-at-end 633 :dark-offset NIL :dark-utilization 0 :max-dark-utilization 1920 :low-sky "N" :pcs-visibility 3142 :pcs-gap 0 ) true 1 0