Principal Investigator Email Address
moffat@astro.umontreal.ca
Estimated Total Execution Time (hours, including overheads)
5:57:52.0
General Description
In this project, we will carry out repeated, AO-assisted, high-S/N, K-band spectroscopy of the three brightest stars in NGC3603, namely the stars A1, B and C. One star, A1, is a known binary with a period of 3.7724 days. In Time-Critical Aspects, we propose (but do not impose) a pattern with which the binary phase can be sampled ~equidistantly. Star C will also act as AO-NGS; therefore, it will be acquired first and centered. Then, the AO loop will be closed, and four exposures of star C will be taken. Then, by the use of pre-defined offsets (i.e., carried out blindly), we will move to star A1 and perform another four exposures. Then, we offset to star B and take four exposures as well. For all offset positions, DIT=21 second. No dithering, no jitter. Note that the P2PP verification tools warns that the specified target will be outside the FOV. This is of course true, but irrelevant, since we will offset to our other two targets. Also note that there will be *no* sky frames at all. See Special Execution Requirements.
Waiver Requests
No Waiver Request was submitted
Critical Observing Condition Constraints
As specified in each individual OB description, seeing has to be 0.8" or better, and the target has to be observed at airmasses of 1.5 or better. This is necessary to achieve the required Strehl ratio and spatial resolution. Twilight observations can be carried out as long as the AO is functioning and delivering the specified Strehl ratio and the sky background in K does not increase. Please note that the airmass constraints lead to observability windows for our target in the range of plus/minus ~3 hours around meridian passage of NGC 3603. See Time-Critical Aspects for further information.
Time-Critical Aspects
While we observe three stars (A1. B and C), star A1 is our primary target, since it is the known double-eclipsing binary (C and B will be monitored). We would like to sample the phase of A1 in ~equidistant way, but as we did not specify time contraints in our Phase I document, we won't specify any time contraints here. However, given the airmass constraints, a window of observability exists only plus/minus ~3 hours around meridian passage of our targets. Given the time of the year, meridian passage happens ~at the middle of the night (not to be confused with midnight) somewhere between April and June We thus propose to observe our targets in 22 ~contiguous nights, where per night, one OB is carried out. This way, each OB is carried out at roughly the same time of the night - of course plus/minus the aforementioned 3 hours, to the discretion of the service observer to maintain high schedulability. Holes due to weather or higher prioritized OBs, even longer than one day, are no problem, just go on with the "schedule" until all 22 visits are carried out. Bunching the OB together will provide good phase coverage while, even if the 6 hour margin around meridian passage is always fully used. IMPORTANT NOTE: Please do under all circumstances avoid that more than one OB is carried out per night!
Special Execution Requirements
While in principle, our observations are straight forward, and once the loop has successfully been closed, all should run by itself. Of course, the real challenge is the acquisition of our target star C (which will also act as AO-NGS) because our three stars are smack in the core of a dense young cluster. Luckily, they are the brightest stars in the field, and thus a short (1s), rather shallow acquisition exposure will make them stand out on the screen. We have provided finding charts (FC) or different quality and format. They have been attached to all observing blocks of this run (cf. end of this text). The 60"x60" chart is taken from 2MASS-K and is rather fuzzy, but seeing and resolution at Paranal will be significantly better. Only star C is indicated as it is the acquisition target. (Stars A1 and C will be reached by offsets.) For your information and as an orientation help, we have thus added two ~30"x30" FCs, namely one rather deep VLT-ISAAC frame (negative of a JHK composite) under 0.4"-seeing conditions, and a HST-WFPC frame taken with the F658N filter aroun Halpha. The ISAAC frame fairly well represents what you will see before closing the AO loop. Your seeing will probably be somewhat worse, but in turn the field will be less crowded due to the short acquisition exposure. As you can see, we have indicated star C and the 8"x8" acquisition box, and it can clearly be identified. For comparison, the WFPC frame shows what you will see once the the AO loop is closed. Note that all stars in the cluster NGC3603 have ~the same spectral type (blue, young, luminous OB stars), so that the field should not much change in the K band. Here, too, the 8"x8" acquisition FOV is indicated. The WFPC frame is rather shallow and therefore matches well the short exposures for the acquisition frames. For the 8"x8" FCs with the 0.8"x0.8" inlet, we have a blow up of the ISAAC frame. Star C is clearly visible, especially in short exposures. For comparison, we also show a WFPC blow-up. Note that the HST PSF matches the VLT PSF quite well once the AO is locked, and that only the brightest star will be visible - you should pretty much see what is visible in the WFPC frame. Thus, it is from the WFPC frame that we have prepared three 8"x8" frames. They are all centered on star C because this star is to be acquired interactively (it is the AO-NGS after all), thus this one will be your concern. But for your information, we have also indicated the two other offset positions (A1 and B) in corresponding frames with the respective 0.8"x0.8" FOV inlets. (Offsets have been obtained from the WFPC frame and are hence of sufficient precision). We have very bright stars with emission lines, so we have computed our DITs so that the peak pixel count stays well below 30,000 e- and the emission lines do not saturate, even if the seeing is 0.6" AND the airmass is 1.2; should you encounter better conditions than that, please adjust to DIT=15sec for the respective OB. Please verify for every OB that no pixel is above 40,000 e-. Note that we do not need to take sky frames because our targets are so much brighter than the sky. Thus, all offset positions generate "Object" frames. Throughout our entire run, no sky frame at all is produced. Filenames for the finding charts attached are: 60by60_2MASS-K.jpg 60"x60" 2MASS-K 30by30_ISAAC-JHK.jpg 30"x30" VLT-ISAAC 30by30_WFPC-F658N.jpg 30"x30" HST-WFPC 8by8_C_AO-NGS_WFPC-F658N.jpg 8"x 8" HST-WFPC star C (AO-NGS!) 8by8_A1_WFPC-F658N.jpg 8"x 8" HST-WFPC star A1 8by8_B_WFPC-F658N.jpg 8"x 8" HST-WFPC star B Good luck and thanks!
Special Calibration Information
None. Baseline calibrations are sufficient.
ToO Information
None.
ToO Activators List
None.
Is this a Pre-imaging run ?
false
Pre-imaging Requirements
None.
Source(s) of Pre-imaging
HST/WFPC2
Pre-imaging sources not listed above
Do all your OBs comply with the instrument-specific requirements listed on the instrument-specific Phase 2 web page ?
If this is a pre-imaging run, did you select PRE-IMAGING for the Observing Category for each Observing Template ?
N/A
Do all your finding charts comply with both the general and instrument-specific Phase 2 Web Pages ?
If you submitted OBs for standard stars, did you specify the magnitude and spectral type of all standard stars in the OBs ?
N/A
Have you included OBs for any calibrations that you need but which are not part of the Calibration Plan ?
N/A
If you are observing Moving Targets, have you attached suitable ephemeris files to your OBs?
N/A
If you have preferences which OBs should be executed first, did you make use of the User Priority field in the OBs ?
N/A
If this is a run that requires coordinated observations with other facilities, did you give proper instructions in the Time-Critical Aspects Section ?
N/A
Did you indicate the magnitude of the brightest object in the field in each SINFONI OB?
If you are using the AO: Did you indicate for every OB the magnitude of the guide star, and its distance to the target (if any)?
If you submitted OBs for standard stars, did you use the provided StandardStar templates?
N/A
If you are using a specific offset pattern or position angle: did you check carefully the definition in the manual?
Did you make really sure that none of your OBs ever saturates the detector?
If you are using the AO: did you enter the correct Strehl Ratio (on-axis, K-band) AND the seeing value in the constraint set?