From denault@irtf.ifa.hawaii.edu Thu Mar 1 17:10:14 2001 Date: Thu, 1 Mar 2001 17:03:08 -1000 (HST) From: Tony Denault To: Jim Elliot , John Rayner Cc: Peter Onaka , amanda@lowell.edu Subject: Spex & occultations Jim/John, there is my summary of the meeting: 1. On March 01, 2001, John Rayner, Tony Denault, and Jim Elliot meet to discuss possible spex modifications to better support occultations. Here is a summary of the issues discussed: 1.1 Display of GPS Lock. Spex displays a warning message if the GPS time and Unix time is off. This indicates a problem with the either the GPS sync or Unix NTP sync. If GPS time-stamping of the data is a requirement, the observers should check status of the GPS receiver and timer board by looking at their panels. Also for occultation run, the day crew should physical check the receiver and timer board status prior to the run. The sparc should be able to read the GPS lock state, but we haven't be able to implement is due to communication problems between the SPARC and timer board. We will try to fix this. 1.2 Allow the option of a second keyboard and mouse so that each camera could be operated by a different person. Observers can run bigdog and guidedog using 2 separate Unix workstations (stefan and boltzmann). This allows different operators to control bigdog and guidedog. 1.3 Have the GPS clock located in the user area for the LED calibration. And have the GPS configured to GMT not local time. We explained the IRTF configured the GPS receiver to local time because the TCS can only accept local time formatted input. The side effect was that the IRIG-B time code outputted to the nfscam and spex is in local time. NSFCAM and spex converts the local time to GMT for the FIT header. The timer board's LED display is in local time. Jim expressed his reservation about the IRTF configuring the GPS for facility purposes, making its configuration less optimal for observing. Jim purchased the GPS and it is on loan at the IRTF to specifically support occultation observing. We agreed that the IRTF shouldn't reconfigure the GPS receiver at the expense of occultation programs and the IRTF should have a separate GPS to support its TCS. 1.4 Include days/hours along with minutes/seconds in the movie time data. Movie mode time stamping is done by embedding the minutes/seconds in the last pixel of each movie frame. Due to problems with image scaling and file output, this pixel is set to 0 when producing FITS files. In order to add the days/hour field, an additional data pixel must be taken away from the image. The trade off of using two pixel to get the GPS days, hour, minutes, seconds in each move frame is acceptable to Jim. Spex should be modified to include this additional data. It was suggest to add a FITS comment stating the last 2 pixel were set to 0. 1.5 Imbed the move frame GPS time-stamp in the FITS header rather that a separate text file. We will try to implement this in a future version of spex. 1.6 Remove padding between n subframes. We expressed a need to preserve the relative spacing of the data in the FITS files. Jim express concern about extra space and time this padding consumed. An option to produced packed or unpacked data was suggested. This is less of an issue since available disk space has been increased, and more software options aren't desired. We haven't committed changing spex to do this but, will keep it in mind. 1.7 Output of the seqtble.spex timing files. An option to output dsp timing information has been added to spex. DSPoutputTiming toggle is located on the setup page. This will produced a timing file (DSPTiming_0004.txt) when the array-clocking tables are calculated for the DSP. Observers should consult with Tony Denault to help extract the information they need, as this information is very verbose. 1.8 Other note: The absolute coordinates of the sub frames are recorded in the FITS header. Tony /--------------------------------------------------------------------------\ | Tony Denault | Email: denault@irtf.ifa.hawaii.edu | | NASA IRTF, Institute of Astronomy | Phone: (808) 933-0893 | | 640 North Aohoku Place | Fax: (808) 933-0737 | | Hilo, Hawaii 96720 | | \--------------------------------------------------------------------------/