ysbach/find_amateur_astro_target

Find which amateur astronomy targets are above the horizon at given time, showing the altitude/airmass plot.

find_amateur_astro_target

Yoonsoo P. Bach (@ysBach)

Finds which amateur astronomy targets that are above the horizon at given time, and showing the altitude/airmass plot.

Catalogs supported at this moment are Messier and Caldwell.

"공개행사"

This work is derived from the "서울대학교 천문대 공개행사" (by SNU astro), a subproject of "서울대학교 연구성과사회환원 프로그램" (by SNU)

• "SNU": Seoul National University, South Korea
• "astro": Department of Physics and Astronomy, Astronomy program

Therefore, the default location/timezone is at Seoul, South Korea.

Install

Dependency

You need:

• python 3.6+
• pytz
• numpy
• pandas
• astropy
• astroquery
• astroplan
• matplotlib
• rich (optional)

First, install Anaconda/miniconda (You may also make a new environment if you wish). Then run this:

$ conda install -c conda-forge rich numpy pandas matplotlib pytz astropy astroquery astroplan --yes

The very first, test run:

$ cd <where you want to save it>
$ git clone https://github.com/ysBach/find_amateur_astro_target.git
$ cd find_amateur_astro_target
$ python find_targets.py -o first_trial.html -t M31

Usage

1. The simplest example

$ python find_targets.py

It will use all ~200 targets, using the current time ± 2 hour at Seoul. Any object above minimum altitude 30˚ will be plotted.

Few of the most widely used examples can be:

$ python find_targets.py YYYY MM DD HH mm ss -d 1 -vA -M
$ python find_targets.py YYYY MM DD HH mm ss -d 2 -vA -t M31 M1 M5
$ python find_targets.py YYYY MM DD HH mm ss -d 2 -vA --min-alt 15 --currentlocation

2. Practical usage for 공진단

2-1. First run

First, check for ALL the objects above the horizon on the day. I will test with

• 2021-11-12 20:30:00 [KST] (given by 2021 11 12 20 30)
• duration of ± 1 hour (given by -d 1)
• I want to see only those are above 30˚ ALL the time (use -A)
• I want to remove those without common nickname (use -N)
• save all target list as test.html (-o test.html)
• use verbose option (-v)

$ python find_targets.py 2021 11 12 20 30 00 -o first.html -d 1 -v -A -N

Output:

Date & Time : 2021-11-12 20:30:00+09:00 (Asia/Seoul)
lon , lat  : 127.00˚, 37.50˚
Only those with common nicknames are selected.
96 objects are selected by the user.
26 objects are visible by the user's criteria.
   gal: 08 objects
   Neb: 13 objects
    cl: 05 objects
others: 00 objects
* Catalog saved to first.html
3 planets are visible under the user's criteria.

Abbreviations for "Type" column
[...]

The plot is messy, but it is intended (because there are 26 objects!).

• NOTE: line style is grouped based on the type of the objects (cluster, neubla, galaxy, otehrs)
• NOTE: For the Moon, θ_full means the 180˚ - (Sun-Earth-Moon angle), i.e., the angle for the Moon to travel to become a full moon.

The output HTML will look something like this:

It shows the ID (C: Caldwell, M: Messier), NGC/IC IDs, common names, etc. On top of these, it gives you link to Wikipedia, and the 35'x35' view by DSS in linear scale and zscale. The red boxes are 21'x21', which is the FoV of SNU-SAO 1m telescope with STX-16803.

2-2. Check for Candidates

Now, considering the time limit and the interest of the audience (e.g., depending on the topic of the lecture given before the observation), let's select few target candidates.

On 2021-11-12, we have a lecture on Sombrero galaxy (M104), but it is not visible, unfortunately. Similar galaxies, S/E types, can be chosen from the list above. I will select M31 (Andromeda), M33 (Pinwheel galaxy), C12 (Fireworks galaxy), C23 (Silver silver galaxy). Also, let me choose an open cluster that may be attractive to general audience, C13 (Owl cluster). I will also add two nebulae, the Cave Nebula, C9, and Little Dumbbell nebula, M76.

2-3. Find Missing "Type"s

Unfortunately, we have no globular cluster! Let's go back to the first step, but now loosen -N (select even though they have no common nickname), but add -T cl-G (only Type == 'cl-G' will be drawn):

python find_targets.py 2021 11 12 20 30 00 -o first-cl-G.html -d 1 -v -A -T cl-G

Considering both the images in first-cl-G.html and the altitude plot above, I think M15 is a good choice.

2-4. Finally: Specify Targets

Finally, select targets by -t M31 M33 C12 C23 C13 C9 M76 M15

$ python find_targets.py 2021 11 12 20 30 00 -o second.html -d 1 -v -t M31 M33 C12 C23 C13 C9 M76 M15

(No need to specify other flags. Even if you use other flags like -ANT, they'll be ignored.)

The plot looks simpler, but you have to note that M72 and M45 can be below altitude 30˚ (the lower limit for SNU-SAO 1m telescope) during the ± 1hour duration.

2-5. Planning

Well, we have very many objects. Moon, Jupiter, Saturn are "must visit" objects. Thus, let me choose only five additional celestial objects: M31 (Andromeda: as it will be mentioned in the 2021-11-12's lecture), C23 (Silver Silver galaxy: edge on galaxy similar to Sombrero, the main topic of 2021-11-12's lecture), M15 (globular cluster: as it is also related to the 2021-11-12's lecture), C13 (Owl open cluster), and a nebula, C9 (Cave nebula).