General description: This is a raw image fresh out of the MARVELS1 instrument, without any modifications. All images, regardless of whether they are science, calibrations, or junk, receive the same naming convention. Good science and calibration images are generally found in the et1/ directory for each MJD, while test images are generally found in the engineering/ directory, although switching directories is up to the observer, so perhaps 1% of the time, the images might be put in the wrong directory.
Naming convention: MARVELS1.YYYY-MM-DDTHH:MM:SS.SSS.fits, where the timestamp is in UTC.
Approximate size: 34 Mbytes.
File type: FITS
Read by products: reduceMARVELS
Written by products:
| HDU | Contents | Description |
| HDU0 | Null data array | Contains only keywords |
| HDU1 | 4096 x 4096 16-bit integer image | Counts in ADU |
| HDU2 | 1x3 32-bit integer array | PMT data |
The EXPTYPE header keyword is automatically filled in by the instrument GUI, so in general is highly reliable for determining the type of image. Some common EXPTYPEs are:
The EXPTYPEs can also receive the suffix NF, which stands for, "no fringes," and indicates that a diffuser screen was inserted after the interferometer in the optical train to blur out the fringes.
The PLATEID keyword indicates the number and side of the piece of aluminium being observed with (e.g., '3060A'). This is entered by the observer, so is subject to typos. It can be 'NULL' or '-9999', since sometimes a plug plate is not being used for the exposure.
The OBJECT header keyword indicates the common name for a plate (e.g., 'FIELD9999' or 'HIP14810'). This is entered by the observer, so is subject to typos. It can be 'NULL' or '-9999', since sometimes a particular set of coordinates is not being targeted by the exposure.
SIMPLE = T / Written by DataAcqServer.cc,v 1.27 2011/08/24 2 BITPIX = 16 / Bits per pixel NAXIS = 0 / EXTEND = T / FITS dataset contains extensions. DATE_FH = '2012:078:03:34:48' / UT of header creation (YYYY:DAY:HH:MM:SS) DATE = '2012-03-19' / Date Format is YYYY-MM-DD TIME = '03:34:48.99' / Start of exposure FILENAME= 'MARVELS1.2012-03-19T03:34:48.990.fits' / Name of Output File FILEDIR = '/data/56005/et1/' / Directory of Output File PMTMSINT= 100 / PMT integration time in milli-seconds PMTCOADD= 10 / number of PMT integrations co-added PMTUPDAT= 1.000000 / seconds between each PMT counts read PMTAVG = 19.000000 / Average PMT counts during obs. PMTRMS = 0.000000 / RMS deviation of PMT counts during obs. PMTMIN = 19 / Minimum PMT counts during obs. PMTMAX = 19 / Maximum PMT counts during obs. PMTCENTS= 2 / offset time of median PMT flux (seconds) ORIGIN = 'SDSS/APO' / FITS file originator INSTRUME= 'MARVELS1' / name of instrument acquiring data DETECTOR= 'SI-620' / name of CCD OBSERVAT= 'APO' / Name of Observatory TELESCOP= 'SDSS_2.5m' / Name of Telescope OBSERVER= 'NULL' / ID of Observer Taking Data JD = 2456005.649167 / Julian date at start of observation MJD = 56005.149167 / Modified Julian date FCJD = 2456005.649190 / Flux centered Julian date ACQTYPE = 'Dark' / type of CCD exp. (Light / Dark / Bias) OBSTYPE = 'SCIENCE' / type of obs. (science / engineering) DATAMODE= 'SAVE' / Disposition of data (i.e. save/discard) USERNOTE= '' / Optional note made by user about obs. UTC-OBS = '03:34:48.8' / UTC of Start of Exp. UTC-END = '03:34:48.8' / UTC of End of Exp. LST-OBS = '08:19:52.254' / LST of Start of Exp. LST-END = '15:06:36.431' / LST of End of Exp. CARTID = -9999 / Cartridge ID no. PLATEID = 'NULL' / APO Plate ID No. OBJECT = 'NULL' / Nickname for plate (eg. 51PEG) EXPTIME = 0.000000 / Length of Exp. (seconds) EXPTYPE = 'BIAS' / Exp. type keyword (from observing GUI) OBSFLAG = 'GOOD' / Exp. Quality Flag (GOOD/BAD/JUNK) SEEING = -9999.000000 / Approx. max. see-ing (PSF max FWHM in arcsec) IMGAVG = 475.175598 / average data value in image IMGMAX = 4006 / maximum data value in image IMGMIN = 436 / minimum data value in image IMAGECNT= 229 / image grab count of DataAcqServer IMAGE_ID= 771 / exposure count of SI-CCD controller SNRMAX = -9999.000000 / maximum Signal/Noise of spectra SNRMEDN = -9999.000000 / median Signal/Noise of spectra SNRMIN = -9999.000000 / minimum Signal/Noise of spectra SNRAVG = -9999.000000 / average Signal/Noise of spectra SNRSTDEV= -9999.000000 / std. dev. of Signal/Noise of spectra BUNIT = 'ADU' / data units are Analog to Digital convert Units GAIN = 1.460000 / gain of readout in electrons per ADU RDNOISE = 4.580000 / Readout noise st.dev. in electrons per pixel RDRATE = 200.000000 / Readout rate in kHz RDPORT = 'A' / Port from which CCD is being read (A/B/C/D) READMODE= 2 / Readout mode number READTIME= 492733 / Length of Readout (seconds) READNOIS= 4.580000 / Readout noise st.dev. in electrons per pixel READRATE= 200.000000 / Readout rate in kHz READPORT= 'A' / Port from which CCD is being read (A/B/C/D) CCD_ATTN= 0 / Analog Attenuation set for CCD CCDSEC = '[1:4096], [1:4096]' / Section of CCD IN USE CRYOCOOL= 1 / Status of CrycoCooler (1=ON/0=OFF) CCDTEMP = -106.300003 / CCD Chip Temp. in Deg. Celsius CCDPRES = 0.001100 / CCD Dewar Pressure in torr CCDSHUT = 1 / Shutter Status During Exposure (1=OPEN/0=CLOSED ICEL-ID = 'NULL' / Unique Name of I2 Cell ICEL-T = -9999.000000 / Mean I2 Temp. in Deg. Celsius ICEL-RMS= -9999.000000 / RMS Temp. During Exp. in Deg. Celsius ICEL-POS= 'NULL' / I2 Cell Pos. (IN/OUT) ECEL-ID = 'NULL' / Unique Name of empty I2 Cell ECEL-T = -9999.000000 / Mean empty Cell Temp. in Deg. Celsius ECEL-RMS= -9999.000000 / Empty Cell RMS Temp. in Deg. Celsius ECEL-POS= 'NULL' / Empty I2 Cell Pos. (IN/OUT) DEWPOINT= -9999.000000 / weatherData (dewpoint) DEWDEP = -9999.000000 / weatherData (dewpointDep) DUSTA = -9999.000000 / weatherData (dusta) DUSTB = -9999.000000 / weatherData (dustb) DUSTC = -9999.000000 / weatherData (dustc) DUSTD = -9999.000000 / weatherData (dustd) GUSTD = -9999.000000 / weatherData (gustd) HUMIDITY= -9999.000000 / weatherData (humidity) HUMIDOUT= -9999.000000 / weatherData (humidout) PRESSURE= -9999.000000 / weatherData (pressure) WINDD = -9999.000000 / weatherData (windd) WINDS = -9999.000000 / weatherData (winds) FBRPOS = 'NULL' / Fiber Position (TELE/CALI/NONE) PHAS1 = -9999.000000 / Mean Phase of Int. During Exp. (radians) PHASRMS1= -9999.000000 / Mean Phase RMS of Int. During Exp. (radians) DENS1 = -9999.000000 / Mean Fringe Density of Int. During Exp. (pix/fr DENSRMS1= -9999.000000 / Mean Fringe Density RMS of Int. During Exp. (pi TILT1 = -9999.000000 / Mean Tilt of Fringes During Exp. (pix) TILTRMS1= -9999.000000 / Mean Tilt RMS of Fringes During Exp. (pix) FOCUS = -9999.000000 / Focus piston (in microns) ALARMOBS= 'none' / Obs. event alarm ALARMTCC= 'none' / TCC access alarm ALARMDCA= 'none' / DC agent alarm ALARMDAS= 'none' / DAS alarm RA = -9999.000000 / RA of tel. boresight in DEGREES DEC = -9999.000000 / DEC of tel. boresight in DEGREES TAIMJD = 56005.149565 / Mod. Julian Date in TAI time EPOCH = 0 / Epoch of Coordinates. EQUINOX = 2000 / Equinox of Coordinates. AZ = 121.000000 / Azimuth (encoder) of tel. ALT = 30.000000 / Altitude (encoder) of tel. ROTPOS = 0.000000 / User spec. rotation angle SHUTTERA= 0 / Shutter A: Sky: 0=closed, 1=open SHUTTERB= 0 / Shutter B: Laser: 0=closed, 1=open THARINT = 45 / ThAr Lamp Intensity (0-100, in integers) TUNGINT = 75 / Tung Lamp Intensity (0-100, in integers) THARLAMP= 'ON' / ThAr Lamp Status (ON/OFF) TUNGLAMP= 'OFF' / Tung Lamp Status (ON/OFF) DIFFUSER= 'OUT' / Diffuser (A) @ OUT FILTER = 'CLOSED' / Filter (C) @ CLOSED IODINE-C= 'IN' / Iodine-Cell (B) @ IN INDEXR-A= 2 / steps from Datum of indexor A (Diffuser) INDEXR-B= 5 / steps from Datum of indexor B (Iodine-Cell) INDEXR-C= 860 / steps from Datum of indexor C (Filter) P1 = 10.4928665 / Mean Pressure(PSI) of Regulator P2 = 10.381666 / Mean Pressure(PSI) of Chamber P3 = 10.405127 / Mean Pressure(PSI) of Atmosphere P1RMS = 0.0016899152 / RMS Pressure(PSI) of Regulator P2RMS = 7.0080464E-4 / RMS Pressure(PSI) of Chamber P3RMS = 0.002076296 / RMS Pressure(PSI) of Atmosphere P1MIN = 10.491531 / min. Pressure(PSI) of Regulator P2MIN = 10.380808 / min. Pressure(PSI) of Chamber P3MIN = 10.403124 / min. Pressure(PSI) of Atmosphere P1MAX = 10.495251 / max. Pressure(PSI) of Regulator P2MAX = 10.3825245 / max. Pressure(PSI) of Chamber P3MAX = 10.407988 / max. Pressure(PSI) of Atmosphere T1 = 28.000099 / Mean Temp. of North in deg. Celsius T2 = 28.000050 / Mean Temp. of South in deg. Celsius T3 = 28.000050 / Mean Temp. of East in deg. Celsius T4 = 28.000151 / Mean Temp. of West in deg. Celsius T5 = 27.999950 / Mean Temp. of Top in deg. Celsius T6 = 28.003050 / Mean Temp. of Bottom in deg. Celsius T7 = 34.998451 / Mean Temp. of CCD skin in deg. Celsius T8 = 28.388048 / Mean Temp. of CCD house in deg. Celsius T1RMS = 0.000830 / RMS Temp. of North in deg. Celsius T2RMS = 0.000589 / RMS Temp. of South in deg. Celsius T3RMS = 0.000669 / RMS Temp. of East in deg. Celsius T4RMS = 0.000572 / RMS Temp. of West in deg. Celsius T5RMS = 0.000669 / RMS Temp. of Top in deg. Celsius T6RMS = 0.000669 / RMS Temp. of Bottom in deg. Celsius T7RMS = 0.002085 / RMS Temp. of CCD skin in deg. Celsius T8RMS = 0.000498 / RMS Temp. of CCD house in deg. Celsius T1MIN = 27.999001 / min. Temp. of North in deg. Celsius T2MIN = 27.999001 / min. Temp. of South in deg. Celsius T3MIN = 27.999001 / min. Temp. of East in deg. Celsius T4MIN = 27.999001 / min. Temp. of West in deg. Celsius T5MIN = 27.998999 / min. Temp. of Top in deg. Celsius T6MIN = 28.002001 / min. Temp. of Bottom in deg. Celsius T7MIN = 34.993999 / min. Temp. of CCD skin in deg. Celsius T8MIN = 28.386999 / min. Temp. of CCD house in deg. Celsius T1MAX = 28.002001 / max. Temp. of North in deg. Celsius T2MAX = 28.000999 / max. Temp. of South in deg. Celsius T3MAX = 28.000999 / max. Temp. of East in deg. Celsius T4MAX = 28.000999 / max. Temp. of West in deg. Celsius T5MAX = 28.000999 / max. Temp. of Top in deg. Celsius T6MAX = 28.004000 / max. Temp. of Bottom in deg. Celsius T7MAX = 35.000999 / max. Temp. of CCD skin in deg. Celsius T8MAX = 28.389000 / max. Temp. of CCD house in deg. Celsius T9 = 59.999550 / Mean Temp. of Iodine_Cell in deg. Celsius T10 = 22.750299 / Mean Temp. of CCD Air in deg. Celsius T11 = 28.191950 / Mean Temp. of ifm_Top in deg. Celsius T12 = 27.909750 / Mean Temp. of Center in deg. Celsius T13 = 28.045250 / Mean Temp. of Grating in deg. Celsius T14 = 27.599548 / Mean Temp. of CCD_area in deg. Celsius T15 = 27.967949 / Mean Temp. of Input in deg. Celsius T16 = 20.835999 / Mean Temp. of Ambient in deg. Celsius T9RMS = 0.000740 / RMS Temp. of Iodine_Cell in deg. Celsius T10RMS = 0.002282 / RMS Temp. of CCD Air in deg. Celsius T11RMS = 0.000589 / RMS Temp. of ifm_Top in deg. Celsius T12RMS = 0.000623 / RMS Temp. of Center in deg. Celsius T13RMS = 0.000623 / RMS Temp. of Grating in deg. Celsius T14RMS = 0.000865 / RMS Temp. of CCD_area in deg. Celsius T15RMS = 0.000805 / RMS Temp. of Input in deg. Celsius T16RMS = 0.006000 / RMS Temp. of Ambient in deg. Celsius T9MIN = 59.999001 / min. Temp. of Iodine_Cell in deg. Celsius T10MIN = 22.743999 / min. Temp. of CCD Air in deg. Celsius T11MIN = 28.191000 / min. Temp. of ifm_Top in deg. Celsius T12MIN = 27.908998 / min. Temp. of Center in deg. Celsius T13MIN = 28.043999 / min. Temp. of Grating in deg. Celsius T14MIN = 27.596998 / min. Temp. of CCD_area in deg. Celsius T15MIN = 27.966000 / min. Temp. of Input in deg. Celsius T16MIN = 20.820999 / min. Temp. of Ambient in deg. Celsius T9MAX = 60.000999 / max. Temp. of Iodine_Cell in deg. Celsius T10MAX = 22.752998 / max. Temp. of CCD Air in deg. Celsius T11MAX = 28.192999 / max. Temp. of ifm_Top in deg. Celsius T12MAX = 27.910999 / max. Temp. of Center in deg. Celsius T13MAX = 28.046000 / max. Temp. of Grating in deg. Celsius T14MAX = 27.601000 / max. Temp. of CCD_area in deg. Celsius T15MAX = 27.969000 / max. Temp. of Input in deg. Celsius T16MAX = 20.845999 / max. Temp. of Ambient in deg. Celsius END
This HDU contains the actual image data.
XTENSION= 'IMAGE' / MARVELS1 CCD image BITPIX = 16 / Bits per pixel NAXIS = 2 / NAXIS1 = 4096 / X dimension of array NAXIS2 = 4096 / Y dimension of array PCOUNT = 0 / required keyword; must = 0 GCOUNT = 1 / required keyword; must = 1 EXTNAME = 'CCD' / Name of the FITS extension. EXTVER = 1 / Number assigned to the FITS extension. BZERO = 32768 / Data is unsigned short integers END
HDU2 (PMT) contains a record of the fluxes of the zeroth-order light from the spectrograph grating, as recorded by a photomultiplier tube. These values serve as a holistic diagnostic of the quality of the exposure, as a function of time elapsed during the exposure. By reading these values, one can tell whether the total light from all fibres plugged was low at any point during the exposure. Some typical reasons for low flux might include cloudy conditions, poor plate scale and focus, or a burnt-out calibration lamp. The PMT flux is also used to determine where the flux-weighted midpoint of the exposure is, which is recorded in the HDU0 keyword FCJD (Flux-Centred Julian Date).
The header keywords for HDU2 are minimal; in order to know the current PMT settings, one must consult the PMT* keywords from HDU0. These include the exposure time per PMT flux point (PMTMSINT) and the time between PMT flux points (PMTUPDAT).
Note that the PMT software was first implemented during on-site commissioning, so the first few days of data taken (prior to MJD 54733) did not yet contain PMT information.
XTENSION= 'IMAGE' / MARVELS1 PMT data BITPIX = 32 / Bits per pixel NAXIS = 1 / NAXIS1 = 3 / X dimension of array PCOUNT = 0 / required keyword; must = 0 GCOUNT = 1 / required keyword; must = 1 EXTNAME = 'PMT' / Name of the FITS extension. EXTVER = 2 / Number assigned to the FITS extension. END