Amateur Spectroscopy

The niche but rewarding end of amateur astronomy: pull a star or nebula's light through a transmission grating or slit spectrograph, image the spectrum on a CMOS, then reduce to a calibrated wavelength-vs-flux curve. Real science contributions: variable star classification, novae confirmations, Be-star emission monitoring, exoplanet atmosphere transits, comet composition. The AAVSO Spectroscopy and Sociedad de Astronomia del Plata databases accept amateur submissions.

For broader citizen science see Citizen Science & AstroBin; for the imaging side that produces the raw spectra see Image Acquisition; for catalogues / reference data see Astro Catalogues & Data.

Free reduction software

• ★ ★ ISIS (Integrated Spectrographic Innovative Software, Christian Buil) — free Win-only. The reference amateur spectroscopy reduction package; calibrates wavelength, flux, atmospheric extinction; produces FITS-compliant 1D spectra; submits to BAA-VSS / ARAS / AAVSO databases. Closed binary, free.
  • http://www.astrosurf.com/buil/isis-software.html
• ★ BASS Project (British Astronomical Spectroscopy Software) — free Win-only. Lighter than ISIS; great for getting started; alkalines into BAA-VSS contribution flow.
  • https://uk.groups.io/g/BassSpectro
• ★ VSpec (Valerie Desnoux, AUDE) — free Win. The classic since the late 1990s; visual spectrum line identification; absorption / emission line measurements; doppler shift; pre-ISIS workflow but still excellent for analysis after reduction.
  • http://www.astrosurf.com/vdesnoux/
• DadosSpec / Tracer3 — free Win; specific to certain spectrograph designs.
• specreduce / specutils (Astropy) — free Python; the academic-grade pipeline; cross-platform.

Hardware — entry / transmission grating

• ★ Star Analyser SA100 / SA200 (Paton Hawksley, UK) — paid (£140). The "first spectrograph": a transmission grating in a 1.25" filter cell. Drop-in; transforms any deep-sky imaging rig into a low-resolution spectrograph. Resolution R100. Resolves Hα emission, identifies spectral classes, sees DOC features in novae. The unambiguous starting point; thousands sold.
  • https://www.patonhawksley.com
• RSpec Explorer (RSpec) — bundle of Star Analyser + reduction software; paid.

Hardware — slit spectrographs (medium-resolution)

• ★ Shelyak ALPY 600 — paid (€2500). 600 lines/mm slit spectrograph; R600; the "step up" from Star Analyser. Comes as ALPY core + guiding module + calibration module. The serious-amateur sweet spot.
• Shelyak LISA — paid (€4500). Higher resolution (R1000); slit + flat-field; the "I'm doing real variable-star monitoring" tier.
• Shelyak eShel / UVEX — paid (€10–15k). High-resolution echelle (R10000+); the dedicated-observatory tier.
• DIY designs (DadosSpec, Lhires III) — instructions and partial kits available; building one is a project in itself.

Calibration

• Reference lamps: Neon-Argon (low-cost), Thorium-Argon (gold standard), built into ALPY/LISA calibration modules.
• Standard stars: bright, well-characterised stars used to remove instrumental + atmospheric response. ISIS / specutils have built-in catalogues.
• Telluric correction: subtracting Earth's atmospheric absorption (water, oxygen) from observed spectra; ISIS handles this.

Submitting data

• ★ BAA-VSS (British Astronomical Association Variable Star Section) — free; takes amateur spectra into shared database.
• ★ ARAS (Astronomical Ring for Access to Spectroscopy) — French-origin; the largest amateur spectroscopy network; free; ~150 observers worldwide.
  • https://aras-database.github.io/database/aras_database.html
• ★ AAVSO Spectroscopy — see Citizen Science & AstroBin.
• CHIRON / SMARTS (pro) — for those who eventually publish.

Practical reality

• Spectroscopy is a smaller community than imaging; expect mailing-list-based forums (Spectro-L, ARAS forum) rather than YouTube.
• A mono CMOS (ASI174MM, ASI183MM, ASI294MM-Pro) is preferred over OSC; full QE on every pixel.
• Tracking quality matters more than aperture for slit work; a 6" SCT on an EQ6 with PHD2 + ALPY produces real data.
• Books: Christian Buil's Astronomical Spectroscopy (2008), Robin Leadbeater's tutorials at threehillsobservatory.co.uk.

What's changing in 2024–2026

• specutils / specreduce maturing as a Python pro/am bridge; cross-platform.
• Pro-am supernova / nova confirmations — amateur spectroscopists routinely classify TNS-discovered transients hours after detection.
• Exoplanet transmission spectroscopy — ALPY-class instruments + Tess / hot-Jupiter follow-up — frontier.
• ARAS Be-star database — continuously growing; landmark amateur dataset.

License / pricing summary

• Free: ISIS, BASS, VSpec, Astropy specreduce/specutils, ARAS submission.
• Paid hardware (entry): Star Analyser ~£140.
• Paid hardware (mid): Shelyak ALPY ~€2500, LISA ~€4500.
• Paid hardware (high): Shelyak eShel ~€10–15k.

Pick this if…

• Total beginner, just want to see Hα in Vega: Star Analyser SA100 + RSpec or ISIS.
• Serious variable-star monitoring: ALPY 600 + ISIS, submit to ARAS.
• Cross-platform Python pipeline: specutils / specreduce on Mac/Linux.
• Pro/am bridge, nova confirmations: ALPY/LISA + ARAS network membership.
• Just curious: start with Star Analyser; you'll know within a month if you want to go deeper.