Date: Sun, 19 Sep 1999 05:01:54 -0600 From: Dan Long Subject: 2.5m obslog 990918 ( MJD 51440 ) SATURDAY SEPTEMBER 18, 1999 APACHE POINT OBSERVATORY SDSS 2.5m OBSERVING LOG Observering team: Dan Long (APO) Stephanie Snedden (APO) Scot Kleinman (APO) Scott Burles (UC) Tonight's plan was to do focal plane mapping until the moon was out of the way, then obtain as much spectrographic data the night would allow. We got the some focal plane data, but as soon as we got the science cartridge on and set up the humidity shot up and we had to close. Sadly, we did not get to reopen. The focal plane data was taken using plate 185 on cartridge 2. The plate was not set up like the older "letter" plates, so we only had one set of guide fiber positions. Scott will get some positions of the science fibers and use those positions as guide fibers and collect more data tomorrow night. The procedure worked well for the place we did take data and Scott has a log of all the details of positions of axes, optics, weather, etc. We are having a little trouble mounting cartridges when there are two on the cart. Sometimes the cart scrapes the lift plate when going over it. The second thing is that when there are two cartridges on the cart and lifting the one furthest from the handle, it occasionally catches on the east corrector latch. The slightest shove to the west will allow it to clear. This is the second time this has happened to me ( once with cartridge 4, and tonight with cartridge 2 ). I suppose it is possible the pressure in the tires is low ( they are pneumatic aren't they? ). What should the pressure be? The science plate we mounted around 23:30 was 214 on cartridge 1. It is still on the telescope. MIRROR NUMBERS Start of the night: Primary: setmir: 0 -7.8 7.8 427 427 galil: 5100, -2700, 200, -6050, 7300, 7000 linear gauges 1 = 1.9310 2 = 0.5575 3 = 0.5565 5 = 1.9060 6 = 0.4070 4 = 0.2610 7 = -6.8750 8 = -0.2940 Secondary: ( inst=spectro focus=1400 alt=18 deg ) setmir: 1400 -0.2 25 0 98.4 galil: 1721250, 1806000, 1764200, -8450, -6950 First set of focal plane data: Air temp: 10.6 Press: 21.54 In Hg Dewpoint: 6.8 ~75% AxePos=31.90,52.78,206.33 Primary: ( scale set to .99985 ) setmir: 1480.8 -7.8 7.8 427 427 galil: -18150, -25950, -23050, -6050, 7350, 7050 linear gauges 1 = 1.9895 2 = 0.6165 3 = 0.6155 5 = 1.9075 6 = 0.4075 4 = -1.2400 7 = -8.3460 8 = -1.7540 Secondary: ( inst=spectro focus=1625 alt=52.8 deg ) setmir: 2851.1 7.5 25 0 -159.6 galil: 3556950, 3641700, 3577250, 8600, 10000 I noticed that the SCALEFACTOR parameter in the tcc is not displayed with enough significance. Tonight when we set it to 0.99985, it showed up as 1.000 ( a significant difference in scale ). TPM data was logged for most of the night in "/mcptpm/tpm51440.dat". A comment on really local weather conditions. It appears that on fairly calm nights ( wind speeds less than 10 MPH at the met tower ) the dewpoint sensor on the 3.5m can be reading a depression of more than 6 C and still we get condensation around the 2.5m telescope ( rails, enclosure skin, top of dog house, etc ). A similar check around the catwalk of the 3.5m shows that things dry off with the depression greater than about 3 C. So I believe the dewpoint sensor is reading correctly, but that the vertically challenged location of the 2.5m makes for a lower humidity threshold on calm nights as read from the dewpoint sensor mounted on the 3.5m. Nitrogen notes: Both spectrographs were filled at 15:00, 20:30 ( once open ) and again at about 05:00. WEATHER Skies tonight were mostly clear at sunset and remained clear or mostly clear all night. Humidity began creeping up after sunset, and around midnight rose to the point where we had to close. It never dried out enough to reopen. Temperatures were around 50 most of the night. Winds were out of the W at less than 10 MPH most of the night. Seeing tonight was between 1.2 and 1.5 arcseconds while DIMM was open ( before midnight ). Dan