Waking up at 12:00 (again), going for lunch, coming back for plat fields, trying to solve the "Neon problem" (Residual Bulk Image), a few mails, a few phone calls, a few tests...
We finally settler for doing some quick darks and bias frames to try and minimize the problem. But this CCD really likes memorizing Ne lines.. It takes time to forget them!
Meanwhile, we decided to tackle the issue of the not-so-good-looking flatfields we were making. We had an intense gradient, and wavy look on our "flats". Later we were reminded that the sensor's sensitivity is it self wavy in aspect. Since a spectrograph physically distributes wavelength on the sensor, it is natural that that something constant is detected by the sensor as darker or brighter in agreement with its sensitivity. The other gradient we have is still unclear in origin. But since a spectrum is only a band of a handful of pixels wide, it doesn't matter! Images that are reduced to produce spectra don't need to be pretty, as noone usually is interested in seeing them.. It is more important that the flat can correctly correct the data, and for that purpose, it works as expected!
During the night, we made 4 20-minute measurements of WR 140, spent some training time trying to point at WR 1, and then 2 more measurements of HD 14134. But we were unexpectedly and abruptly interrupted by a "100% humidity" smell inside the dome! In 20 minutes, humidity had risen from 45% to 100% outside.. We were forced to close the dome, before outside temperature would reach -2.1ºC (dew point at -1.6ºC). These temperatures explain how our car got covered in a bubbly spray of ice! Quite interesting to the touch, but very uncomfortable to stay outside touching it in the cold wind.
Well, a side-effect of this "unfavorable" weather, is that the cumulative 8 hours we had of sleep in the past two mornings, were finally going to be payed back between our pillows and our warm sheets!
Our elephant-memory sensor was left powered on, making dark and bias exposures, during our night of sleep...
Well, I did dedicate part of my sleep time to write the recent posts that should have been written from two days ago..
Subscribe to:
Post Comments (Atom)
No comments:
Post a Comment