MOSFIRE Data Format

MOSFIRE raw data files are in FITS format with five extensions, but only the first, or primary header/data unit (HDU) contains the science data. The primary HDU consists of the two standard FITS components: (a) an ASCII text header holding a list of keywords that describe the data unit, and (b) the binary data following it. For a description of the keywords in the MOSFIRE primary HDU, visit http://www2.keck.hawaii.edu/koa/public/keywords/mosfireKeywords.php. The primary image header is populated with the world coordinate system (WCS) information, providing access to orientation, handedness, and astrometry. The other four extensions following the data are ASCII tables listing a number of attributes for the science targets, as well as the slit configurations for the science and alignment objects. Below is a listing of the attributes contained in these HDUs:

==================== HDU 2: ASCII Table ====================

43 header keywords

Target_List (11 columns x 31 rows)

Col# Name (Units) Format
1 Target_Name A8
2 Priority A7
3 Magnitude A5
4 RA_Hours A2
5 RA_Minutes A2
6 RA_Seconds A5
7 Dec_Degrees A2
8 Dec_Minutes A2
9 Dec_Seconds A5
10 Epoch A6
11 Equinox A6

==================== HDU 3: ASCII Table ====================

49 header keywords

Science_Slit_List (12 columns x 31 rows)

Col# Name (Units) Format
1 Slit_Number A2
2 Slit_RA_Hours A2
3 Slit_RA_Minutes A2
4 Slit_RA_Seconds A5
5 Slit_Dec_Degrees A2
6 Slit_Dec_Minutes A2
7 Slit_Dec_Seconds A5
8 Slit_width (arcsec) A5
9 Slit_length (arcsec) A6
10 Target_to_center_of_ A6
11 Target_Name A8
12 Target_Priority A7

==================== HDU 4: ASCII Table ====================

31 header keywords

Mechanical_Slit_List (6 columns x 46 rows)

Col# Name (Units) Format
1 Slit_Number A2
2 Target_in_Slit A8
3 Target_Priority A7
4 Position_of_Slit (ar A7
5 Slit_width (arcsec) A5
6 Target_to_center_of_ A5

==================== HDU 5: ASCII Table ====================

58 header keywords

Alignment_Slit_List (15 columns x 5 rows)

Col# Name (Units) Format
1 Slit_Number A2
2 Position_of_Slit (ar A8
3 Slit_width (arcsec) A5
4 Target_to_center_of_ A6
5 Target_in_Slit A8
6 Target_Priority A5
7 Target_Magnitude A5
8 Target_RA_Hours A2
9 Target_RA_Minutes A2
10 Target_RA_Seconds A5
11 Target_Dec_Degrees A2
12 Target_Dec_Minutes A2
13 Target_Dec_Seconds A5
14 Target_Epoch A6
15 Target_Equinox A6

MOSFIRE uses a single Teledyne Hawaii 2RG HgCdTe 2K x 2K detector, with a pixel scale of 0.180 "/pixel. The full detector characteristics can be found here. The image pixels are in 32-bit floating points, with a full-frame raw image containing 16,853,760 bytes.

A software package is available for reducing MOSFIRE data. Details on how to obtain and install the package are provided on the MOSFIRE data reduction pipeline page.

More information is given on the Keck MOSFIRE page and the UCLA MOSFIRE page.