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I was looking to find some example carbon star spectra and came across this page on the Harvard website which shows several plots of carbon star spectra. The horizontal axis is labelled as wavelength in ångströms, but the vertical axis appears to be labelled with "g-98" which I am not familiar with - any idea what quantity this is?

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    $\begingroup$ This is a guess, but it could be the result of a text wrapping bug. The top line of each plot ends with "Mon [time] 03-Au", and if you append "g-98" to this, you have a date: August 3rd, 1998, which is presumably when the plots were generated. $\endgroup$
    – HDE 226868 ♦
    Apr 24, 2019 at 23:56
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    $\begingroup$ @HDE226868 is right. These plot are made in IRAF, which writes the dates exactly there. If you google iraf spectrum, you'll find similar plots. The standard header is something like "NOAO/IRAF [version] [user-email] [date] [file name] [title]" $\endgroup$
    – pela
    Apr 25, 2019 at 6:29
  • $\begingroup$ @pela - great, thanks. Put that as an answer and I'll accept it. $\endgroup$
    – user24157
    Apr 25, 2019 at 7:04
  • $\begingroup$ I think @HDE226868 deserves that credit :) $\endgroup$
    – pela
    Apr 25, 2019 at 8:12
  • $\begingroup$ Links rot over time so I've captured an example plot so that future readers will be able to understand the question if the page is ever moved or deleted. $\endgroup$
    – uhoh
    Apr 25, 2019 at 22:52

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It looks like the floating "g-98" is just an extension of the header of the plot (made by IRAF), which has wrapped around the image for lack of room on the right-hand side. Looking at the N0 plot, we see that the header should read

NOAO/IRAF V2.10.4EXPORT perry@sparky.sao.arizona.edu Mon 06:04:51 03-Aug-98

which just contains information about the software, user and creation date behind the plot.

(Hat tip to Pela for confirming my guess!)

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