Creating a Recipe File for Beginners
In order to reduce data from a night using the IGRINS PLP (v3 recommended), you’ll have to create a recipe file which tells the PLP which files belong to which objects and what type of reductions the PLP should follow for that object. Creating a recipe file is outlined in depth on the IGRINS PLP Wiki, but the primary steps are repeated here for reference.
Table of contents:
Field Descriptions
These are the columns (in order) in the recipe file with each column separated by a ,:
OBJNAME: name of the object observed (ie. K Tau)
OBJTYPE: object type for pipeline reduction, only commonly used types listed here
TAR: target or sky frame
STD: standard star
FLAT: flat calibration frames
GROUP1: the first OBSID (file number) in the series of exposures taken for an object
GROUP2: the GROUP1 value for the corresponding standard star to divide a particular target by
EXPTIME: the exposure time of the frames (in seconds)
RECIPE: the recipe type the PLP should use for the data reduction
FLAT: only use with FLAT calibration files
SKY: use for the SKY frame for the night
These recipes always use optimal extraction (if your data is in focus, not a double star, and the trace looks clean this is okay to use!):
A0V_AB: a standard A-B (on-slit) nod sequence for an A0V star
A0V_ONOFF: an ON-OFF (slit) nod sequence for an A0V star
STELLAR_AB: a standard A-B (on-slit) nod sequence for a target
STELLAR_ONOFF: an ON-OFF (slit) nod sequence for a target (most appropriate in the case a point source, like a star, has an extended disk; frames taken must be ON/OFF type not A/B)
These recipes use sum extraction (if your data is out of focus* or the target fills the slit this is best to use!):
EXTENDED_AB: an A-B (on-slit) nod sequence for extended objects (not point sources)
EXTENDED_ONOFF: an ON-OFF (slit) nod sequence for extended objects (not point sources)
OBSIDS: a list of all the file numbers to stack separated by a space
FRAMETYPES: the corresponding frame type for each OBSID, will either be A/B (if nodded on the slit) or ON/OFF (if nodded off the slit) separated by a space
*It is not typical to reduce point sources with an extended recipe and it will lower the SNR of the data, but if the optimal extraction fails for your data this is the only other reduction option available to try to recover the data. You will have to divide the 1D target spectrum by the 1D A0V spectrum if A0V division is required, currently IGRINS PLP does not support extended recipe division.
Note: FLAT frames and one 300 second(-ish) SKY frame is required for the IGRINS PLP to run.
Simple Recipe Example
File name: 20241206.recipes
OBJNAME, OBJTYPE, GROUP1, GROUP2, EXPTIME, RECIPE, OBSIDS, FRAMETYPES
FLAT, FLAT, 11, 1, 300, FLAT, 11 12 13 14 15 16 17 18 19 20, OFF OFF OFF OFF OFF ON ON ON ON ON
k Tau, STD, 21, 1, 20, A0V_AB, 21 22 23 24, A B B A
XZ Tau, TAR, 25, 21, 100, STELLAR_AB, 25 26 27 28 29 30 31 32, A B B A A B B A
Orion Bar, TAR, 33, 1, 300, EXTENDED_ONOFF, 33 34 35 36 37 38 39 40, ON OFF OFF ON ON OFF OFF ON
SKY, TAR, 41, 1, 300, SKY, 41, ATips!
If you are working with a night that has no dedicated sky frame ( booo womp womp):
Use a single frame (A or B) from a dim target taken in the night or an OFF frame (if any were taken), the longer the exposure time the better!
Make sure the GROUP1 value does not match another GROUP1 value in the recipe! Pick a frame in the center of an existing observation to ensure overwriting does not occur.
No dim targets observed that night? Borrow a sky frame from a nearby night by copying the SDCH and SDCK file numbers into your indata directory and change the civil date in the file name (important! if you don’t do this the PLP will not find them!)
If the file number of the sky already exists in your indata directory, add a 9 to the front (i.e. 95 ->995)
If you are working with a night that has no flat frames (*audible booing*):
The only option here is to steal flat frames from a neighboring night and follow the same copying and renaming convention as outlined for the sky frames above.