starteller-cli 2.0.1

A command-line tool for astrophotographers to find optimal viewing times for deep sky objects

StarTeller-CLI

A comprehensive command-line tool for astrophotographers and telescope enthusiasts to find optimal viewing times for deep sky objects throughout the year.

Given your location, StarTeller scans about one year of local nights. For each object it picks the best night: the one with the longest stretch of time where the object is above your minimum altitude during astronomical darkness (Sun more than 18° below the horizon). If two nights tie on that duration, the night with the higher peak altitude within the visible segment wins. Coordinates are precessed from J2000 to an epoch near the middle of the night list before the scan.

Installation

Install from PyPI (Recommended)

pip install starteller-cli
starteller

That's it! The starteller command will be available in your terminal.

Install from Source (Development)

If you want to modify the code or install the latest development version:

git clone https://github.com/ConnRaus/StarTeller-CLI.git
cd StarTeller-CLI
python -m venv venv
source venv/bin/activate  # On Windows: venv\Scripts\activate
pip install .
starteller

Or run directly without installing:

git clone https://github.com/ConnRaus/StarTeller-CLI.git
cd StarTeller-CLI
pip install -r requirements.txt
python src/starteller_cli.py

How it works

1. Enter your coordinates (or use a saved location)
2. Set your output directory (or use a saved preference)
3. Set minimum altitude
4. Get a CSV with optimal viewing times for ~13,000 deep sky objects

The first run downloads the NGC catalog and addendum (~4MB). Night darkness times are computed each run from your location and a rolling ~365-day window from today’s date.

Output

Results go to ./starteller_output/ by default, or a custom directory you set on first run. CSV columns are written in this order:

Column	Description
Object	NGC/IC/Messier ID
Name	Common name if available
Type	Galaxy, Nebula, Cluster, etc.
Messier	Messier number if applicable (e.g., M31)
Constellation	IAU constellation (from catalog)
Right_Ascension	Right ascension in degrees (J2000)
Declination	Declination in degrees (J2000)
Major_Axis_arcmin	Major axis angular size in arcminutes
Minor_Axis_arcmin	Minor axis angular size in arcminutes
Position_Angle_deg	Position angle of major axis (N through E)
V_Mag	Visual magnitude (catalog)
SurfBr	Surface brightness (catalog)
Best_Date	Local calendar date of the best night (longest qualifying dark-time span, not “at midnight”)
Best_Time_Local	Local time of the peak used for that night (within the visible segment, toward transit when possible)
Max_Altitude_deg	Approximate altitude at that peak on the best night, or Never visible if no night qualifies
Azimuth_deg	Azimuth at peak (0°=N, 90°=E, etc.)
Rise_Time_Local	Local time the object crosses up through your minimum altitude on that best night’s segment (HH:MM)
Rise_Direction_deg	Azimuth at rise
Set_Time_Local	Local time it crosses down through minimum altitude on that segment (HH:MM)
Set_Direction_deg	Azimuth at set
Observing_Duration_Hours	Hours above your minimum altitude during astro dark on that best night only (not summed over the year)
Visible_Nights_Per_Year	Count of nights in the scan with any time above min altitude during astro dark
Dark_Start_Local	Start of astronomical darkness on the best night (HH:MM local)
Dark_End_Local	End of astronomical darkness on the best night (HH:MM local)
Timezone	IANA timezone name used for local times

Options

Filters and flags:

• Minimum altitude (prompt, default 20°): the object must reach this altitude during astro dark for a night to count; the best night maximizes the length of that interval.
• starteller --messier-only: only Messier catalog entries are processed (smaller CSV).

Included catalogs:

The output includes all ~13,000 objects from NGC, IC, Messier, Caldwell, and other catalogs from OpenNGC (subject to the Messier-only flag above). The full catalog can be found on my fork of OpenNGC here.

File locations

Data and settings are stored in platform-specific directories:

Windows: %LOCALAPPDATA%\StarTeller-CLI\
Linux: ~/.local/share/starteller-cli/
macOS: ~/Library/Application Support/StarTeller-CLI/

This includes the NGC catalog, your saved location, and output directory preference. Output CSVs go to your configured output directory (default: ./starteller_output/).

Requirements

• Python 3.10+
• Internet connection (first run only, to download catalog)

Dependencies: pandas, numpy, tzdata (IANA DB for zoneinfo), timezonefinder, tqdm

Data source

Catalog data comes from OpenNGC by Mattia Verga, licensed under CC-BY-SA-4.0.

License

AGPL-3.0-or-later (GNU Affero General Public License v3). See LICENSE.

The NGC catalog data is CC-BY-SA-4.0.