Tips & Tricks

Pro tips to help you find more exoplanets and avoid common pitfalls. From beginners to advanced users.

Quick Tips

Start with Known Planets

Practice on confirmed exoplanets like TOI-700 or Kepler-11 before searching for new candidates. This helps you understand what real transits look like.

Check Stellar Type

M-dwarfs (red dwarfs) are ideal for finding small planets because their small size makes transits deeper and easier to detect.

Look at the Phase-Fold

The phase-folded light curve shows all transits stacked. A clear, consistent dip is a good sign. Noisy or irregular dips may be false positives.

Use Multiple Sectors

TESS observes targets multiple times. Combining sectors increases signal strength and helps confirm period accuracy.

Finding Good Targets

Best Star Types for Planet Hunting

Star Type Advantages Challenges
M-dwarf Deeper transits, shorter periods, habitable zone closer Fainter, more flares, potentially tidally locked planets
K-dwarf Good balance of transit depth and stellar activity Moderate transit depth
G-dwarf Sun-like, well-understood physics Shallow transits for Earth-sized planets
F-dwarf Bright, good photometry Faster rotation, harder to detect small planets

What Makes a Target Observable

  • Brightness (V mag < 12): Brighter stars have less photometric noise
  • Low stellar variability: Active stars with spots can mask or mimic transits
  • Not in crowded field: Nearby stars can dilute transit signal or cause confusion
  • Multiple observation sectors: More data = better detection confidence

Avoiding False Positives

Common False Positive Sources

Up to 50% of transit candidates turn out to be false positives! Here's how to identify them:

Eclipsing Binaries

Signs:

  • Transit depth > 5% (most planets are < 2%)
  • Secondary eclipse visible at phase 0.5
  • V-shaped transit (planets have flat bottom)
  • Odd-even depth differences

Action: Check for secondary eclipse and depth asymmetry

Background Eclipsing Binary

Signs:

  • Centroid shifts during eclipse
  • Transit depth changes with aperture size
  • Nearby bright star in the field

Action: Run centroid analysis, check different apertures

Stellar Variability

Signs:

  • Irregular transit timing
  • Transit shape changes between events
  • Strong rotation signal in light curve

Action: Run VSTAR-001 to classify variability type

Instrumental Artifacts

Signs:

  • Transit occurs at same spacecraft time
  • Signal correlates with CCD column
  • Multiple stars show same "transit"

Action: Check quality flags, compare nearby stars

The Vetting Checklist

  1. Is the transit depth physically reasonable? (< 5% for planets)
  2. Is there a secondary eclipse? (Suggests EB)
  3. Are odd and even transits the same depth? (Different = EB)
  4. Does the centroid stay stable? (Shift = BEB)
  5. Does depth change with aperture? (Yes = contamination)
  6. Is the period stable across sectors? (Variable = stellar)

Improving Detection Success

Optimize Your BLS Search

Parameter Default When to Adjust
period_min 0.5 days Increase to 1+ day if looking for habitable zone planets around Sun-like stars
period_max 15 days Increase for long-period planets (needs more data)
duration_grid 0.01-0.15 Narrow for known stellar type; widen for exploratory searches

Dealing with Noisy Data

  • Use sigma-clipping: Remove outliers that can confuse the BLS algorithm
  • Try different detrending: Polynomial may work better than spline for quiet stars
  • Bin the data: For very noisy data, binning to 10-30 minute cadence can help
  • Combine sectors: More data always helps for marginal detections

Finding Multi-Planet Systems

Many stars host multiple planets! After finding one transit:

  1. Subtract the best-fit transit model from the data
  2. Run BLS again on the residuals
  3. Look for additional periods in the periodogram
  4. Check for TTVs (Transit Timing Variations) - a sign of unseen planets
"Find additional planets after removing the first signal"
"Check for transit timing variations"
"Look for additional periods in the residuals"

Advanced Techniques

Transit Timing Variations (TTVs)

If transits don't happen exactly on schedule, there might be another planet gravitationally tugging on the transiting one.

  • Measure individual transit times precisely
  • Calculate O-C (Observed minus Calculated) residuals
  • Look for periodic patterns in the residuals
  • TTVs are strongest near mean-motion resonances (2:1, 3:2)
"Analyze transit timing variations"
"Calculate TTV for each transit"
"Check for mean-motion resonance"

Combining TESS and Kepler Data

Some targets were observed by both missions. Combining data:

  • Improves period precision (longer baseline)
  • Helps detect long-period planets
  • Enables TTV analysis over decades
Note: Different instruments have different systematics. Normalize and detrend each dataset separately before combining.

Single Transit Events

Sometimes only one transit is observed. These are hard to confirm but can be valuable:

  • Long-period planets (P > observation baseline)
  • Need follow-up observations to confirm period
  • Can estimate minimum period from transit duration
"Analyze single transit event"
"Estimate period from duration"
"Flag for follow-up observation"

Keyboard Shortcuts

Shortcut Action
Ctrl + Enter Send message
Ctrl + K Quick search
Ctrl + / Show commands
Ctrl + S Save current analysis
Ctrl + P Generate report
Esc Cancel current operation

Common Mistakes to Avoid

Ignoring Stellar Parameters

Planet radius depends on stellar radius. If the star's size is wrong, your planet size will be wrong too. Always verify stellar parameters.

Over-Aggressive Detrending

Too much detrending can remove the transit signal along with stellar variability. Start with gentle detrending and increase only if needed.

Trusting Low-SNR Detections

Signals with SNR < 7 are often noise. Require higher confidence before claiming a detection. When in doubt, get more data.

Not Checking for Harmonics

The BLS might pick up a harmonic (half or double) of the true period. Always check the phase-fold at 2x and 0.5x the detected period.

Ignoring the Odd-Even Test

Eclipsing binaries often show different depths for alternating eclipses. Always compare odd and even transit depths before validating.

Pro Tips from the Community

"When vetting, I always look at the target pixel file directly. Sometimes the aperture includes flux from a nearby eclipsing binary."
- Sarah K., Citizen Scientist
"Multi-sector targets are gold. I found my first validated planet by combining 4 TESS sectors - the signal was marginal in each alone."
- Michael T., Amateur Astronomer
"Don't skip the boring step of checking against known EB catalogs. You'll save hours of work on false positives."
- Dr. Emily R., Astrophysicist

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