CCD: FULL 13'x13' READOUT: ONE AMP GAIN INDEX: 1 Read Noise ~ 1.5 ADU = 5.5 e- FILTER SET: UBVRI ----------------------------------------------------------------------- NOTES FOR TARGET FIELDS ----------------------------------------------------------------------- 1. At the beginning of each day, i.e., in the afternoon before the observing, use "epar obspar" and set the next observation number to 1001 for n1, 2001 for n2, etc. 2. In the afternoon take 10 zero-second bias frames using "zero". 3. Also in the afternoon, take 10 dome flats (punto blanco) in each of the two filters (B,V). My experience was that the exposure times needed was 100 seconds for the B filter and 60 seconds for the V filter (in wheel 1). In wheel 2 it is necessary to use the colour balance filter for the dome flats. 4. Just after the Sun sets, and in the morning just before the Sun rises, take skyflats. This are taken with the telescope pointing at the zenith. Here timing is everything. Put tracking on so that there are no star trails, only stars (seen only with the longer exposures). Try to adjust your exposure time so that you get average count levels between 10,000 (=10K) and 30K; however, counts between ~5K and ~40K will be useful. At sunset start with the B filter then do the V filter, then do the B filter, then the V filter, etc. Keep increasing the exposure times from 2 seconds until you reach 300 seconds. Aim for 5 B and 5 V skyflats. 5. The observing program is simple, only two globular star clusters in the LMC, NGC2257 and NGC2210. There are no calibration fields because each field already has been calibrated internally. Edgardo Cosgrove made guide star charts for a zero point star (HR441?) and for the two clusters and they are in the observing room. The coordinates for these two fields are: NGC2257 RA 06:30:12, DEC -64:19:36 NGC2210 RA 06:11:31, DEC -69:07:18 6. The sequence I found best was to take 4 exposures of NGC 2257 (B,V,B,V) and then 4 exposures of NGC 2210 (B,V,B,V), all exposures being 400 seconds. Initially I used the command "obj" and did them one filter at a time, checking the focus after each. At the beginning of the night the focus was found to be ~38100 when the telescope temperature was 19.0 deg Celsius; then at the telescope cooled to around 16.5 deg Celsius the focus increased to 38200. After a while I would use "doobs" to do the B and V pictures in pairs (B,V) and then check the focus after the first pair. The focus was checked using "disp obj10xx 1; imexam" and doing the imexam commands "r", "j" and "k". I recorded the FWHM values for each. Usually the "r" FWHM was smaller than for "j" and "k". The goal was to have the "j" and "k" values be similar, which gave round images. There is a poster in front of ctioA4 describing the direction to move the focus to improve the roundness of the images, being aware of backlash. 7. All night long keep alternating between NGC 2257 and NGC 2210, taking BVBV pictures of each cluster. I found I was able to take about 50 object pictures each night. 8. Since this is a time-series photometry program please check that the UT on the TCS clock agrees with the UT being recorded in the header file (at least to within one second). ----------------------------------------------------------------------- NOTES FOR CALIBRATION FIELDS ----------------------------------------------------------------------- 10 bias frames in afternoon sky flats (B,V) at the beginning of the night 5 bias frames during the night sky flats (B,V) at the end of the night 10 bias frames at the end of the night (no photoelectric standard star fields necessary) ----------------------------------------------------------------------- OBSERVING SEQUENCE ----------------------------------------------------------------------- TARGET NGC2257 PRIORITY 1 COORDINATES 06 30 12.0 -64 19 36 (2000.0) FINDER CHART cluster will be obvious AIRMASS less than 2 FILTER(S) B,V,B,V INTEGRATION(S) 400s, 400s, 400s, 400s TOTAL TIME 9 min x 4 = 36 min NOTES Any conditions acceptable TARGET NGC2210 PRIORITY 1 COORDINATES 06 11 31.0 -69 07 18 (2000.0) FINDER CHART cluster will be obvious AIRMASS less than 2 FILTER(S) B,V,B,V INTEGRATION(S) 400s, 400s, 400s, 400s TOTAL TIME 36 minutes NOTES any conditions acceptable, dither 2 arcsec between exposures repeat these all night long in