Date:
Tuesday, April 2, 2013
Telescope:
CTIO Blanco 4-m
Submitter:
Nick Mostek
Submitter Email:
Observer Support:
Hernan Tirado
Night Assistant:
Alberto Alvarez
Also Present:
Eric Huff, Chris Morrison
Problems:
We again had difficulty pointing the telescope at the beginning of the night and lost 1/2 hour. Attempts to recenter the telescope through TCS behaved opposite of the intended direction. We also found that a large slew to our first target caused the pointing to be offset by 6 arcmin in RA. Recommend observers recenter the telescope after all slews >20 degrees.
It was discovered that the DECam system had a temperture anomoly (2-4 degree C swing) this afternoon due to a vacuum pump failure. Measurements of the flat field before and after the incident did not seem to show any large or unusual changes to the focal plane response.
Program:
Proposal:
2013A-0741
Target of Oportunity:
No
Time Observed:
9.0
Time Engineering:
0.0
Time lost technical:
0.5
Time lost weather:
0.0
Time lost other:
0.0
Description:
An i-band survey of the Equatorial Sky for MS-DESI
Primary Investigator:
David Schlegel
Email:
Institution:
Lawrence Berkeley National Laboratory
Instrument:
CTIO 4m DECam
Total Program Time:
9.5
| Total Times | Time Observed | Time Engineering | Time lost technical | Time lost weather | Time lost other | Total Program Time |
|---|---|---|---|---|---|---|
| 2013-04-02 | 9.0 | 0.0 | 0.5 | 0.0 | 0.0 | 9.5 |
Printer-friendly version
End of Run Comments and Suggestions for DECam
1) Pointing issues seem to continue with the telescope. We built in large overlap in our fields, so this was not an issue. However, some observers may not be so careful. Must recommend recentering the telescope after slews >20 degrees.
2) More Information needs to be made available to observers before their run, particularly in the usage and operation of the Quick Reduce software. While QR is very userful for monitoring Background and seeing, we would have very much liked to be able to use the source extractor functionality to better effect during the run. CTIO should make the QR documentation available as well as source extractor configuration files. Observers should be able to readily obtain reduced images and catalogs.
3) DECam desperately needs a more transparent tool for diagnosing image depth on the fly. Determining the 5 sigma point source detection limit for a given filter should be possible for every exposure given DECam's stable functionality. QRs methods for doing so are confusing and not very trustworthy (like Mag_auto calibration from NOMAD galaxy counts for z-band).
4) Observers need to be made aware the internet resources are limited. It is not possible to scp / rsync full images during the course of the night. Further, X-windows applications from external facilities are unusably slow without the help of bandwidth-optimized applications (like NX). Observers need to be ready to evaluate data locally and not depend on transferring data outside the usual daily download to NOAO / NVO / NCSA. If such restrictions remain, we highly recommend increasing the software versatility and processing power of Observer2.
5) Kentools is fairly useful, but again could really use a routine to evaluate image depth and interact with ds9. The online ETC spreadsheet does not seem accurate for galaxy photometry in conditions with >1" seeing.
6) Recommend that Observing assistants be available at the telescope and in the control room no later than sunset. We had a night (Mar. 31) where no one was availble well into twilight.
7) Observer2 needs to be better organized with designated observer scratch space and standardized software installations. WCSTools is a must. IDL needs idlutils / sdsstools / coyote packages. IRAF tools need to be set up to work seemlessly with MOSAIC data (mscdisplay, mscimexam, etc). Also, it is imperative that CTIO make available the DECam map of CCD IDs into the fits header extensions. Single-chip operations in IRAF require the fits extension no, not CCD number or Chip ID. We understand that this mapping in the fits can change...but a WCSTools script routine could be easily written to update the map for any input image.
8) We were very pleased with the seemless operations of the SISPI software with TCS control. It was essential to minimizing overheads in our survey. Pointing errors still need to be corrected / reduced. SISPI sometimes becomes unresponsive and could stand to use a little kick in speed. Loading and manipulating script position in the queue could use bigger buttons and arrows to move highlighed scripts up / down (instead of dragging and dropping). Stop / Go button should be made into two toggles.
9) The Image Health/telemetry viewer, while very useful, probably doesn't need multiple measures of ellipticity and seeing. Replacing one of these with a measure of sky brightness or depth would be useful.
Conclusion
CTIO needs to take some time to improve the observer interface with DECam data. Observers want to interface with their data quickly and accurately so that adjustments can be made during precious observing time. Making documentation and software available prior to the run would have been very helpful, and moving limited amounts of data to external facilities for evaluation is critical in many cases.