WIYN Telescope , Comet Hale-Bopp

Hydra & Densepak Multi Object Spectroscopy

NEW !   The First International Conference on Comet Hale-Bopp was held at Puerto de la Cruz, Tenerife, Spain,  February 2 - 6 , 1998.  A postscript  preprint of our contributed paper can be downloaded by clicking HERE.

Between 1996 October and 1997 April the WIYN Observatory 3.5-meter telescope and its Multi- Object Spectrograph were used to obtain medium resolution spectra of the coma of Comet Hale-Bopp. Most of the spectra were at a resolution of about 15,000 and covered the spectral region 6100A to 6400A. Two different fiber cables were used to feed the MOS, the Hydra and the Densepak. An example of the spectra is shown below:

Click on the above graph to download for a full size PostScript file.

Below is a journal of the observations:

UT AirMass Exp Exp Fiber Wave length Sun-HB Earth-HB Scale Geo-Cent P.A.
Date Begin/End Begin/End No. Time Feed Center Range Dist.(au) Dist.(au) km/min R.V. km/s AntiSun
10/22/96 2:54/3:53 2.61/4.94 4 600 Hydra48 6250 300 2.636 3.049 1.33E5 2.25 79.2
10/23/96 2:51/3:33 2.61/3.87 4 600 Hydra48 5610 280 2.624 3.051 1.33E5 1.92 78.7
10/24/96 1:46/3:14 1.78/3.41 7 600 Hydra48 6250 300 2.613 3.052 1.33E5 1.60 78.2
3/2/97 11:37/13:08 5.16/2.14 12 300 Hydra96 6250 300 1.055 1.467 6.40E4 24.4 330.7
3/16/97 12:16/12:58 4.21/2.88 7 240 Hydra96 6250 300 0.956 1.330 5.80E4 -8.42 349.6
3/18/97 12:07/13:04 5.04/2.88 11 180 Densepak 6250 300 0.946 1.322 5.76E4 -5.66 353.6
3/19/97 12:05/13:10 5.56/2.99 12 240 Densepak 6250 300 0.942 1.319 5.75E4 -4.26 355.8
4/21/97 2:41/3:39 2.29/3.72 10 240 Hydra96 6250 300 0.981 1.604 6.99E4 27.9 61.9
4/25/97 2:55/3:57 2.61/5.51 11 240 Densepak 6250 300 1.009 1.670 7.28E4 29.0 67.9
4/26/97 2:50/3:35 2.54/4.03 8 120 Densepak 6203 3000 1.016 1.687 7.36E4 29.2 69.2
The original data set is made up of 86, 1050 x 2048 pixel CCD images of the comet spectra , plus an even larger number of bias, flat field, wavelength calibration, flux standards, and sky brightness frames . The data have been accordingly processed yielding some 7452 individual ( 1 x 2048) flux calibrated spectra.

Further analysis of these spectra has focused on the extraction of individual spectral feature Intensities (surface brightnesses). In particular for purposes of technique development we have concentrated on two nights, one Hydra night (1997 March 16) and the next Densepak night (1997 March 18....March 17 was lost to bad weather).

We have chosen three species for initial examination; 1) the red auroarl forbidden line of neutral oxygen, 2) a feature due to water molecules which have been stripped of one electron, and 3) the daughter molecular radical which results when an ammonia molecule looses one of its Hydrogen atoms.

Below are links to pages with details on [OI] , H2O+ and NH2

The Neutral Oxygen Data

...Click on this mini-densepak image for [OI] details

Ionized Water Data

....Click on this mini-hydrapak image to get H2O+ details .

NH2 Data

...Click on the WIYN imager frame to get details on NH2

....Ok, Ok, that is indeed an IMAGE of the Comet and out of the goodness of my heart I'll let you have a closer look by clicking on this thumbnail. But only if you promise that when you lie down, when your rise up and when you are on your way, you will chant :

"One SPECTRUM is worth a thousand pictures ! "

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