[vsnet-chat 1981] Re: (fwd) Sequence for M88 supernova / magnitude IR ?

[aah@nofs.navy.mil]

My sn1999cl image posted on
  http://ftp.nofs.navy.mil/pub/outgoing/aah/temp/sn1999clj.jpg
was taken a couple of days after the discovery, and is
a J-band (1.2micron) image.  Note that the SNe is very bright
compared with optical images taken about the same time, so the
high optical extinction mentioned by others is probably correct.
  Unfortunately, this image was taken during non-photometric
conditions so I cannot provide any calibration (if Llapasset
was indeed requesting JHK photometry; my reading of the forwarded
email was just a request for R/I-band secondary standards).
Besides, with my small field of view, all you see is the nucleus
and the supernova anyway!
  Regarding Brian's comments:  JHK are 1-2 micron, not 2-5micron
and are considered "near-IR" in the current terminology.  Johnson
selected J (1.2micron) and K(2.2micron) when setting up his
infrared extension of his wide band system; later, observers
noted that there was another atmospheric window at 1.6microns
and labelled it "H" since it was the letter code closest to the
IJKLM sequence. (Similar problems are arising with the brown
dwarf spectral type assignments:  L comes close to M; T is just
a letter that has not been used before!)
Arne

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