WIYN 3.5m WHIRC Observing Report for 2015/04/10

Summary:
A good night.  3 supernovae, and 1 standard star.
Had second half of night.

Name                    | z       | B-Peak   | 20150405
iPTF15xi                | 0.04    | 20150327 | 41,41,..
ASASSN-15fj             | 0.045   | 20150316 | ..,41,..
ASASSN-15fs             | 0.02902 | 20150401 | 16,22,19

S791-C in JHKs at 1.3

Observer: Michael Wood-Vasey
Telescope Operator: Karen Butler
Conditions: Clear
Wind: 10-25 mph
Humidity: 10-40%
Temperature: 10-14 C
Seeing: 0.6-0.9"
Moon:  59%, rose at 00:37 MST

Notes:
 * Time on ASASSN-15fs was similarly overkill, but was last target of the night and just kept pushing until the OA made me stop.

 * 347 total images taken.   
 The skip from obj_088 to obj_146 was just a bookkeeping error.
 No images are missing -- There are no obj_089-obj_145.

 * Pyraf really is Python, so the following snippet is useful to look at the last image minus the previous image
 just cut and paste the following into the Pyraf terminal

def compare(im1, im2, imtmp="../mwv.fits"):
    iraf.imdelete(imtmp)
    iraf.imarith(im1, "-", im2, imtmp)
    iraf.display(imtmp,2)
    iraf.imexam()

def check(objnum):
    im1="obj_%03d" % (objnum  )
    im2="obj_%03d" % (objnum-1)
    compare(im1, im2)

And then you can run

--> compare("obj_030.fits","obj_029.fits")
to do
 * subtraction of the two files
 * display them to ds9 (frame 2)
 * launch imexam

For convenience, 'check' takes an obsnumber and automatically 'compares' against the previous one.  E.g., the following are equivalent:

--> check(30)
--> compare("obj_030.fits","obj_029.fits")

I couldn't figure out the PYTHONPATH or such for the Pyraf,
 so a civilized "from compare import *"
 for the file named compare.py in the observer@dust home directory didn't work.

MWV is a bit embarrased it took him several years to think of doing this.