中美掩星觀測計畫 之次秒口徑誤報分析

False Alarms in Sub-Second Aperture Photometry with TAOS Telescopes

黃孝智(Shiaw-Chih Huang)

指導教授 ： 闕志鴻

國立臺灣大學/理學院/物理研究所/碩士(2004年)

https://doi.org/10.6342/NTU.2004.01447

摘要

中美掩星觀測計畫的主要目的是直接測量彗星核大小達到只有幾公里的古柏帶的數目。一個掩星事件的機率低到讓我們需要去處理每年一千億筆的測量。在靠近黃道面和銀河的交界處的數個選取的星場的初步注視模式和拉鍊模式影像已經得到，他們是被兩台小型(口徑為五十公分)，短焦比(f值為1.9)，寬視野(三個平方度)配備著兩千乘上兩千個畫素的CCD的自動觀測望遠鏡取得。
由於每秒五次的資料取得，資料簡化的速率是很緊要的，使得數以千計的星球的光度分析必須即時的處理。然而，為了鑑定和了解誤報分析，先前取得的資料已經在離線時分析了。
大部分與拉鍊模式影像有關的光通量變化的分析困難已被解決。在每個被測量的星場裡約有四百顆星球，其極限星等約13.5等。在一千萬筆的測量分析中，取五倍標準差的誤報分析率(3.2×10E-7)與理論值(2.9×10E-7)是符合的。

關鍵字

中美掩星計畫 ； 口徑分析

並列摘要

The objective goal of the TAOS project is to directly measure the number of Kuiper Belt Objects (KBOs) down to the typical size of cometary nuclei (a few km). The probability of such occultation events is so low that we will need to conduct 100 billion measurements per year in order to detect the ten to four thousand occultation events expected.
Preliminary images in both the "stare" mode and the "zipper" mode have been obtained for several selected star fields near the intersection of the ecliptic and the Milky Way. They are taken from two small (20 inch), fast (f/1.9), wide-field (3 square degrees) robotic telescopes, each of which equipped with a CCD camera with pixels of 2k by 2k. The speed of the reduction is critical since data are taken at 5 Hz so that thousands of stars have to be treated within 0.2 seconds since the photometry has to be completed in real time. However, the data have been analysed in off line for the identification and understanding of the false alarms by IRAF under LINUX.
Most of the analytical difficulties related to zipper mode have been solved. Right now, the number of measured stars is about 400 in each field, and the limiting magnitude of measurement is about 13.5. The false alarm rate (3.2×10E-7) coincides with the theoretical value (2.9×10E-7) of 5σ for 10E8 measurements.

並列關鍵字

TAOS ； aperture photometry

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