General

Description	File	Date
Bad pixel map. Value 1 = bad pixel. Full frame (1024x512) Strip mode (1024x300) Stamp mode (400x200) Substamp mode (100x50) (Or see Full Frame and Sub Frame Formats for how to crop the full-frame images yourself.)		Calibrated 2013/02/13 from data from December 2012
Linearity calibration. Documentation (PDF) and IDL code (.pro) to correct linearity.	WARNING: YOU MUST FIRST DIVIDE BY THE NUMBER OF COADDS WARNING2: LINEARITY DATA TAKEN FOR DETECTOR TEMP=55 K and BIAS VOLTAGE VOS=2.5 V. ONLY VALID FOR THESE VALUES - CHECK YOUR FITS HEADER.	Calibrated 2013/04/10 from data from April 2013 -- NOT VALID FOR 2014B DATA. Check your FITS header. The linearity data have Temp1=54.999K and VOS=2.5 Volts (Bias voltage). Only valid for these parameters.
Plate scale and instrument angle ("North_Clio"), and IDL program to rotate North up (.pro).	Get Platescale and NorthClio instrument angle at Astrometric Calibration DEROT = ROTOFF-180+NORTHCLIO To rotate your images to get North up: Rotate COUNTER-CLOCKWISE by angle DEROT.	Calibrated 2013 from data from December 2012

Description

File

Date

Bad pixel map. Value 1 = bad pixel.

Full frame (1024x512)
Strip mode (1024x300)
Stamp mode (400x200)
Substamp mode (100x50)

(Or see Full Frame and Sub Frame Formats for how to crop the full-frame images yourself.)

Calibrated 2013/02/13 from data from December 2012

Linearity calibration. Documentation (PDF) and IDL code (.pro) to correct linearity.

WARNING: YOU MUST FIRST DIVIDE BY THE NUMBER OF COADDS
WARNING2: LINEARITY DATA TAKEN FOR DETECTOR TEMP=55 K and BIAS VOLTAGE VOS=2.5 V. ONLY VALID FOR THESE VALUES - CHECK YOUR FITS HEADER.

Calibrated 2013/04/10 from data from April 2013 -- NOT VALID FOR 2014B DATA. Check your FITS header. The linearity data have Temp1=54.999K and VOS=2.5 Volts (Bias voltage). Only valid for these parameters.

Plate scale and instrument angle ("North_Clio"), and IDL program to rotate North up (.pro).

Get Platescale and NorthClio instrument angle at Astrometric Calibration
DEROT = ROTOFF-180+NORTHCLIO

To rotate your images to get North up:
Rotate COUNTER-CLOCKWISE by angle DEROT.

Calibrated 2013 from data from December 2012

Linearity notes:

Relevant lines of the linearity program, in IDL:

;; Linearity coefficients measured on Comm2 March-April 2013

coeff3 = [112.575 , 1.00273 , -1.40776e-06 , 4.59015e-11]

;; Only apply to pixels above 27,000 counts in de-coadded frames.

for n=0L,n_elements(im)-1 do if im[n] gt 2.7e4 then $

im[n] = coeff3[0] + coeff3[1]*im[n] + coeff3[2]*im[n]^2. + coeff3[3]*im[n]^3.

LINEARITY WARNINGS:
The linearity correction is a correction to the raw pixel count. Therefore, it must be applied to the raw pixels, after data have been de-coadded (divided by the number of coadds). The FITS keyword is called COADDS.

LINEARITY VALIDITY:

The linearity data were taken when the detector temperature Temp1=54.999 K and the bias voltage VOS=2.5 V. These values are sometimes changed from run to run, so check your FITS headers for these keywords (TEMP1 and VOS) to see if this linearity correction is valid for your data. Katie Morzinski is working on a new linearity correction for different settings. Thanks.

Rotation notes:

To rotate your images to get North up: Rotate COUNTERCLOCKWISE by the DEROT angle.
(In IDL that means you have to multiply the angle by minus one)
Relevant lines of the derot (rotate-north-up) program, in IDL:
angle = rotoff - 180 + north_clio
derot_image = rot(image, -1.*angle, cubic=-0.5)

Flats

Camera	Filter	Flat field and Description	Date	Quality Note
Narrow camera
Narrow	H + PK50	Took 9 images (60 sec, 1 coadd) of dawn sky, subtracted mean (of 10) 60-sec darks from each, normalized all to same median, then mean-combined all 9 into 1 image, finally made the median within the good pixel region equal to 1.	From twilight at end of night 2014/04/02-03 (UT 140403)
Narrow	Ks + PK50	Took 5 images (120 sec, 1 coadd) of bright dusk sky, subtracted 5 images (120 sec, 1 coadd) of dark dusk sky, then mean combined and normalized so that the median within the good pixel region is equal to 1.	From twilight at start of night 2014/04/13-14 (UT 140414)	OK. Can still see thermal pupil glow in upper center. Need to try flats with mirror covers closed.
Wide camera
Wide	Ks + PK50
Wide	Ks + PK50	Took 10 images (60 sec, 1 coadd) of dawn sky, subtracted mean (of 10) 60-sec darks from each, normalized all to same median, then mean-combined all 10 into 1 image, finally made the median within the good pixel region equal to 1.	From twilight at end of night 2014/04/07-08 (UT 140408)	Unfortunately, the darks are noisier than normal, so this set has extra noise at the high-spatial-frequencies.
Wide	Ks + PK50	Took 10 images (60 sec, 1 coadd) of bright dawn sky, subtracted mean (of 10) 60-sec dark-twilight(dusk)-sky in Narrow camera (Note the wrong camera), then mean-combined all 10 into 1 image, finally made the median within the good pixel region equal to 1.	From twilight at end of night 2014/04/07-08 (UT 140408)	Not ideal. You can see the thermal pupil glow in upper center that didn't subtract out.