<p>我正在从维齐尔下载星表(使用astroquery)。有关的星表不包括恒星名称,所以我是从辛巴德(也使用astroquery)通过查询我的维齐尔星表中每颗恒星1弧秒范围内的所有辛巴德恒星得到这些名称的。你知道吗</p>
<p>然后我需要按ra/dec坐标进行匹配。然而维齐尔和西姆巴德的坐标可能有点不准确,所以我不能做一个精确的匹配。你知道吗</p>
<p>我目前的解决方案是指定一个公差,对于每一个维齐尔星,调用下面的函数在西姆巴德星之间循环,测试坐标是否在指定的公差范围内一致。作为一个双重检查,因为恒星可以非常接近,我还检查了星等是否匹配到0.1 mag以内</p>
<p>这一切工作,但维齐尔目录的c.2000恒星和类似大小的辛巴德数据集需要2分钟以上运行。我在想办法加快速度。你知道吗</p>
<pre class="lang-py prettyprint-override"><code> def get_simbad_name(self, vizier_star, simbad_stars, tolerance):
"""
Searches simbad_stars to find the SIMBAD name of the star
referenced in vizier_star.
A match is deemed to exist if a star in simbad_stars has both
ra and dec +/- tolerance of the target vizier_star and if their V
magnitudes, rounded to one decimal place, also match.
Parameters
==========
vizier_star : astropy.table.Row
Row of results from Vizier query, corresponding to a star in a
Vizier catalog. Columns of interest to this function are:
'_RAJ2000' : float [Right ascension in decimal degrees]
'_DEJ2000' : float [Declination in decimal degrees]
'Vmag' : float [V magnitude (to 3 decimal places)]
simbad_stars : list of dict
List of star data derived from a Vizier query. Keys of interest
to this function are:
'ra' : float [Right ascension in decimal degrees (ICRS/J2000)]
'dec' : float [Declination in decimal degrees (ICRS/J2000)]
'Vmag' : float [V magnitude (to 3 decimal places)]
'name' : str [SIMBAD primary id of star]
tolerance : float
The tolerance, in degrees, to be used in determining whether
the ra/dec coordinates match.
Returns
=======
name : str
If match then returns the SIMBAD name. If no match returns
an empty string.
Notes
=====
simbad_stars are not all guaranteed to have Vmag. Any that don't are
ignored.
"""
for item in simbad_stars:
try:
approx_Vmag = round(item['Vmag'],1)
except KeyError:
continue
if ((vizier_star['_RAJ2000'] > item['ra'] - tolerance) and
(vizier_star['_RAJ2000'] < item['ra'] + tolerance) and
(vizier_star['_DEJ2000'] > item['dec'] - tolerance) and
(vizier_star['_DEJ2000'] < item['dec'] + tolerance) and
(round(vizier_star['Vmag'],1) == approx_Vmag)):
return item['name']
return ''
</code></pre>
<p>评论之后还有一些想法:</p>
<p>比赛的成功率很高(约99%),所以在几乎所有情况下,循环都会提前退出。它不必迭代所有的星。你知道吗</p>
<p>如果我按ra对simbadè星进行预排序,并使用二进制切分得到循环开始位置的索引,我可以进一步改进。你知道吗</p>