Seestar Photometry Guide: How to Use the New Feature for Variable Stars and Citizen Science

Introduction — For most owners, a Seestar is a machine for beautiful pictures. With the Seestar app update released in October 2026, ZWO added something different: a Photometry feature that measures how bright stars are and how that brightness changes over time. That is the starting point of a lot of real science — variable stars, eclipsing binaries, asteroid rotation and more.

In this guide we explain what Seestar photometry actually does, what is still unknown about it, how precise a small smart telescope can realistically be, and which citizen-science projects can genuinely use your data. As always on this blog, we will be clear about limits as well as possibilities.

• 1. What is photometry?
• 2. The new feature
• 3. How precise?
• 4. Five projects
• 5. Workflow
• 6. Where to send data
• 7. Exoplanets?
• 8. Other smart telescopes
• 9. FAQ

1. What is photometry?

Photometry simply means measuring the brightness of a celestial object. Plot those measurements over time and you get a light curve — a graph that reveals what the object is doing: a star pulsating, two stars eclipsing each other, an asteroid rotating.

Amateurs almost always use differential photometry: the brightness of the target is compared with nearby comparison stars in the same image. Because thin cloud, haze or a change in altitude affect all the stars in the frame in a similar way, the comparison cancels much of that variation.

2. What the new Seestar Photometry feature does

The official release notes of the Seestar app list "Added Photometry" among the new features. Other additions in the same update are also relevant to science-minded users: Motion Monitoring, Smart Tracking with automatic detection of moving objects, Comet Nucleus Stacking, and Dark Frame Library management with an improved dark-frame capture and calibration workflow.

ZWO has not yet published a detailed tutorial or a technical description of the method. This is what we know, and what we don't:

Andy Wilson, Database Secretary of the BAA Variable Star Section, welcomed the feature as an excellent introduction to photometry and a great education tool. He also explained that the magnitudes it produces cannot yet be accepted into the BAA database, because researchers need to know exactly what those numbers represent. He hopes ZWO will publish how the photometry is calculated.

3. How precise can Seestar photometry be?

The best answer comes from the AAVSO Smart Telescope Working Group, a team of about a dozen people studying exactly this question. Their conclusion: by averaging the data from multiple images, they consistently get errors below 0.02 magnitudes — measured against standard stars — with the Seestar S50, and probably with other smart telescopes too.

The chart below puts that number in context. The shaded area is the measurement noise of averaged Seestar data. A brightness change must stand well above it to be measured reliably.

Real-world examples back this up:

• A BAA/AAVSO observer measuring the recurrent nova T Coronae Borealis (around mag 10 at the time) reached a standard deviation of about 0.01 mag by averaging ten 10-second measurements.
• Another observer reported that groups of about 2 minutes of total exposure (12 × 10 s) gave check-star scatter below 0.02 mag.

Which stars can you measure?

The Seestar has a colour (RGB) sensor. The AAVSO recommends treating it like a DSLR and following its DSLR photometry guidelines. Many observers measure only the green channel and report it as TG. Very bright stars saturate easily, and faint stars get noisy.

4. Seestar photometry projects: five realistic ideas

Each card shows how large the signal is and how you observe it. The exoplanet "boss level" is included for comparison.

For asteroid work, the Minor Planet Center (MPC) states that a portable telescope set up regularly in your backyard is "permanent enough" to apply for an observatory code.

5. How to do Seestar photometry: a practical workflow

What improves results the most:

1. 1
   Choose a suitable target. Pick a star within the comfort range (about mag 8–12), with comparison stars of similar brightness and colour in the same field. Observe it high in the sky.
2. 2
   Use EQ mode for long sessions. An experienced observer on the AAVSO forum calls it a key enabler for long photometric series, because it removes field rotation. → See our Seestar EQ Mode Guide.
3. 3
   Save every frame. Enable saving of individual frames (FITS) in the advanced settings. In May 2026 a BAA observer reported that recent stacked images were saturating while the individual subs were fine.
4. 4
   Consider slight defocus. On an S30, one BAA observer found that auto-focused images gave more scatter than slightly defocused ones. Too much defocus, though, can stop plate solving from working.
5. 5
   Calibrate. Use dark frames, now easier to manage with the Dark Frame Library, and flats where possible.
6. 6
   Measure with established software. AAVSO VPhot can demosaic Seestar FITS files. Other common choices are ASTAP, Phoranso and AstroImageJ.
7. 7
   Average, don't over-interpret. Group several frames per data point, and always check your check-star scatter before trusting a dip.

6. Where to send Seestar photometry data (AAVSO, BAA, MPC)

Requirements change over time: always check each program's current documentation before submitting.

7. What about exoplanets?

It is the question everyone asks. Here is the honest answer.

• NASA Exoplanet Watch states there is no telescope size limit, but its reference instruments are around 6 inches (15 cm).
• Smart telescopes have contributed to real discoveries — but larger ones. The best-documented case is TOI-4465 b, a giant planet first seen by NASA's TESS satellite. Its roughly 12-hour transit was captured by observers worldwide, including 24 citizen scientists, many from the Unistellar network (114 mm and 85 mm telescopes). The confirmation was published in The Astronomical Journal (2025).
• With a Seestar the record is mixed. A ZWO presentation (August 2025) relayed a report by two users who detected the transit of XO-6 b with an S50. Other owners have publicly documented repeated failed attempts.

Same noise, two signals: why an eclipse is easy and a transit is not

Both curves have exactly the same measurement scatter. A 0.6 mag eclipse stands out clearly; a 0.015 mag transit is almost lost in the noise. Simulated data, not real observations.

8. How other smart telescopes compare

• The AAVSO Smart Telescope Working Group has reported a timestamp (DATE-OBS) problem in Dwarf 3 raw FITS headers. That matters for any time-series work.
• Unistellar remains the benchmark for organised smart-telescope science. Seestar's strength is its huge user base and, now, built-in photometry.

9. Short FAQ

Conclusion

The Photometry feature doesn't turn a Seestar into a professional observatory, and the method ZWO uses still needs to be documented. But it marks a real shift: a telescope bought for pictures can now measure. That opens the door to contributions that end up in the same databases professional astronomers use.

Start simple — an eclipsing binary, T CrB, an asteroid — and build good habits: saved frames, EQ mode, calibration, averaging. The data will improve, and so will your understanding of the sky.

Here at Astrofaber, we will keep following how this feature evolves. You can find our other Seestar guides on the Astrofaber blog.