Using RV FXCOR package

rohit wrote on Sep 28, 2007

I have been working on high-resolution NIRSPEC data obtained from KECK to calculate radial velocities. I have reduced the spectrum of a target of unknown RV (call the file tar.fits). When I open this target in IRAF using splot, I can use shift+ ( or ) to move through something. Are these orders? apertures? The splot window has the following: [tar.fits[*,27]]: INDEF ap:27 beam 0. Now when using shift + ( or ) the values "27" changes. It ranges from 0 to 84. Is this a multi-dimensional spectrum? If so how do you make it into a 1-D spectrum? I am interested in values of 25,26 and 27.

Please let me know!

Thanks in advance!

---

Ivan Ramirez wrote on Sep 28, 2007

In practice orders and apertures are the same, although sometimes the number of the order has physical meaning (order of dispersion, a gratting property or something like that). What you have is a one-dimensional spectrum because it has already been extracted from a 2d image. I know it's confusing to call it 1d even though there are many orders. But anyway, you can extract a particular order using scopy; for example in your case you could try:
cl>scopy tar.fits tar25.fits aperture=25
This will create a fits file called tar25.fits that contains only the aperture (or order) #25.

---

Last post on Sep 28, 2007