George Jacoby George Jacoby 1 0 2000-09-17T17:42:00Z 2000-09-17T17:42:00Z 46 17062 81900 2408 998 119437 9.2720

NOAO CCD MOSAIC IMAGER USER MANUAL

(KPNO System)

Version: September 15, 2000

George Jacoby
With contributions from

Taft Armandroff, Todd Boroson, Jim De Veny, Steve Heathcote, Buell Jannuzi,
Tod Lauer, Phil Massey, Rich Reed, Frank Valdes, David Vaughnn



The Rosette Nebula (courtesy Travis Rector, NOAO) at the KPNO 0.9-m telescope

[send comments on manual to jannuzi@noao.edu]


1.  Mosaic Overview: At Least Read This!


General Characteristics:

Arrays:

8 2048x4096 SITe CCDs; thinned , science grade

Image size:

8192 x 8192 @ 16 bits, plus header, overscan:~135 Mbytes

Pixels size:

15-um (0.26"/pixel at the 4-m; 0.43"/pixel at the 0.9-m)

Read-noise:

~6 e-

DQE:

86% peak at 6500 (average for 8 CCDs; see also Figure 3.1.2)

Dark-current:

~5 e-/pixel/hr

Read-out time:

2.6 minutes

CCD Gaps:

~0.7 mm (~50 pixels) in rows; ~0.5 mm (~35 pixels) in columns

Cosmetics:

Good to excellent: typically 2 bad columns per CCD, but many 2-8 pixel areas of 5% variation (flatfield completely) and some very large areas of 10% variations that all flatfield to <0.5%

Filters:

5.75"x5.75"; parfocal, 26 filters now available (UBVRI; see Sec 2.6)

Saturation:

Typically, linear to 0.1% to 70,000 e-

Gain:

~3 e-/ADU

4-Meter Parameters:

Count Rates:

At UBVRI=20th mag: U: 35; B:330; V: 340; R: 410; I: 225 e-/sec

FOV:

36'x36', XIMTOOL Orientation: North- left, East-down

Scale:

0.26"/pixel at center; decreases quadratically by 6.5% out to corners

Image quality:

PSF quite constant across the FOV, but ~6% larger in linear scale at the corners

Artifacts:

Faint ~2600-pixel wide donut ghost (~1% at UI, 0.8% at BVR, 2-4% in narrow-band filters).

Typical focus:

-9900 at ~17C (-10200 for U); change with temperature: -90 units per degree C

ADC:

Atmospheric Dispersion Correction: For broad-band filters, use ADC in "track mode" with appropriate filter selected. For flat-fields and narrow-band exposures, use the "null" position or closest broad-band filter mode in wavelength.


0.9-Meter Parameters:

Count Rates:

At UBVRI=20th mag: U: 2; B: 14; V: 15; R: 16; I: 9 e-/sec

FOV:

59'x59', XIMTOOL Orientation: North-left, East-up

Scale:

0.43"/pixel

Image quality:

PSF fairly constant across the field, but a 2-3 focus unit tilt is present.

Typical focus:

4410 at 10C (4413 for U); change with temperature +1.8 units per degree C.


Data Acquisition: Acquisition commands are given on computer named rush -- Analysis commands are given on a computer named driftwood or pecan



All the Commands That Are Likely To Be Needed



Observing Commands (rush)

observe

take one or more exposures prompting for the exposure type

doobs

a script which takes flats/objects for a list of filters

mosdither

takes (typically 5) dithered images in a single filter to fill the gaps in array

more

take more exposures just like the last one

test

take a test exposure. The output image, test, is overwritten each time

object

take one or more object exposures

zero

take one or more zero (bias) exposures

dark

take one or more dark exposures

dflat

take one or more dome flats

sflat

take one or more sky flats

focus

take a focus frame

recover

recover data (if possible) following a crash during readout


Exposure Control Commands

pause

pause exposure (e.g. clouds) [do not ABORT or STOP from within pause!]

resume

resume a paused exposure [then ABORT or STOP if necessary!]

tchange

increase or decrease the exposure time

stop

stop an exposure (and sequence of exposures) reading out the detector

abort

abort an exposure (or sequence) discarding the data

pictitle

change the title of the picture


Quick-look and Taping Commands (driftwood/pecan)

mscdisplay

display an entire mosaic frame

mscexamine

general tool for examining images

mscwfits

write mosaic frames to tape in multi-extension FITS format

Caution :Tape your data as you go; DLT-7000 (~250 images/tape) and Exabyte drives (~35 images/tape) are available. Write time: ~75 seconds/image to DLT, ~3 minutes/image to Exabyte. DDS-4 DAT drive available on Pecan (4m); write time ~40s/image. DDS-2 drive is available at 0.9-m via the network to Taupe (~4 min/image). Please be off the computer by noon of your last day!

You can buy DLT and Exabyte tapes on the Kitt Peak, but bringing your own is cheaper.

Calibration data:

Take dome flats or, preferably, twilight flats (night sky flats work even better!)

Take dark exposures of similar length to your science exposures.

Take zeroes (i.e., biases) -- Darken the dome for darks and zeroes!

Table of Contents


This page was last updated on September 17, 2000
Please send comments or questions to jannuzi@noao.edu.