Документ взят из кэша поисковой машины. Адрес оригинального документа : http://www.naic.edu/vscience/schedule/tpfiles/HowelltagA1656tp.pdf Дата изменения: Thu Apr 7 05:00:58 2005 Дата индексирования: Sat Dec 22 22:31:54 2007 Кодировка: Поисковые слова: arp 220

Proposal Identification No.:

A1656

Date Received:

2005-Feb-28 12:35:00

Technical Page
Proposal Type: General Category: Sub-Category: Observation Category: Total Time Requested: Prop osal Title: ABSTRACT: Urgent Astronomy Spectroscopy Solar System 10 Hours

Spectroscopic Observations of Comet Ikeya-Zhang (P/2002 C1)

Comet Ikeya-Zhang (P/2002 C1) is observable from Arecib o b etween Feb 28 and Apr 2 2002, and again in late May 2002. The OH line strength, which dep ends critically on the relative motion of the comet and the sun, is greatest b efore March 12, and after March 24. On March 13, 18-23 and 28, the line inversion is zero, predicting no OH maser pumping. However, we observed comet LINEAR 2001/WM1 at near zero inversion, and saw the line in absorption when red-shifted, and in emission when blue-shifted, since the gas outflow velo city is a significant fraction of the total radial velo city with resp ect to the sun. The detailed line shap e is a direct measure of the outflow velo city, which is an imp ortant parameter in the interpretation of sp ectral data at other wavelengths. Radio frequency lines are one of the only ways to directly observe the outflow velo city. We prop ose 5 days of observations, 3 for OH line mapping in a hexagonal pattern around the nucleus, one b eam width away from the nucleus, oriented along the sunward-tailward direction. The remaining 2 days we will attempt to observe the formaldehyde line at 4.83 GHz. This bright comet, with predicted water pro duction of 10 29 molecules/second, should have a high enough formaldehyde abundance to observe this line, assuming nominal values for organic materials. The organic abundance is also seen to vary by factors of 20 or more in different comets, so the line could b e much stronger than the nominal prediction. Both formaldehyde and OH observations are imp ortant to determine the ratio, since this daytime comet will not b e observed optically until well after p erihelion.

Name Ellen S. Howell

Institution Arecibo Observatory

E-mail ehowell@naic.edu

Phone 787-878-2612 x282

Student no

Service Observing Request

Remot e Observing Request

X

None All of the observing run. Part of the observing run. Queue Observing

X

No Maybe Yes

Instrument Setup
L-wide C 1


Atmospheric Observation Instruments:

Sp ecial Equipment or setup:

none

RFI Considerations Frequency Ranges Planned
1665-1667 4830

2