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Helpful Guide for Classifying Light Curves

Started by Tom128
Default_user
almost 8 years ago

With more members classifying Light Curves (LC) lately, here is an assembled list of links that may help explain some of the questions in the LCs you see. The first link is the Planet Hunters Tutorial which is a must read.

Bookmark this page for easy reference.

Once you have spent some time with the Tutorial and are now classify light curves, a very helpful link is the Consolidated List of Glitches and other data errors that often masquerade as transits. Posting this link in any comments discussing glitches may be helpful to newer members.

Except for the PH Tutorial, the following links are not listed in any type of priority arrangement:

Planet Hunters Tutorial

http://www.planethunters.org/site_guide

Easy way- Looking ahead thru the light curve quarters 4-6 for potential drops

http://talk.planethunters.org/help/discussions/DPH100suml

Consolidated List of Light Curve Data Glitches through the quarters (by zoo3hans).

http://talk.planethunters.org/discussions/DPH1003diq?page=2&per_page=10&ticket=ST-1316882462rE088B3F238595A9DF7

Kian Jek's famous planetary calculator. Just plug in the values

http://www.kianjin.com/pcalc.html

More efficient ways to hunt planets (More info on member's use of planetary calculator and other tidbits.)

http://talk.planethunters.org/discussions/DPH1011mbd?page=1&per_page=10

Screening for background stars using "Sky View" (Looking for nearby stars that may be contaminating the light curve.)

http://talk.planethunters.org/science/discussions/DPH1003dcx

Look up Kepler stars on International Variable Star Index (VSX)

http://talk.planethunters.org/help/discussions/DPH1014lmf

Examples of Variable Stars in Kepler data base

http://kepler.nasa.gov/science/about/targetFieldOfView/stellarVariability/lightcurves/

List of Kepler False Positive Light Curves

http://archive.stsci.edu/kepler/false_positives.html?print=1

Note: This table will be changed in 2013 and you will be able to retrieve info from KOI catalog here:

http://archive.stsci.edu/kepler/koi/search.php

Stellar Classification Reference- Spectral star types with quick guide for type of possible stars you may see DSCT, RR Lyrae etc.

(by nighthawk_black)

http://talk.planethunters.org/help/discussions/DPH100i9qz

Kepler Planet Candidates

http://archive.stsci.edu/kepler/planet_candidates.html

Note: This table will be replaced in 2013 with KOI catalog here:

http://archive.stsci.edu/kepler/koi/search.php

Listed Eclipsing Binary Stars

http://keplerebs.villanova.edu/

Listed RR Lyrae Stars

http://arxiv.org/abs/1007.3928

Variable Stars

Veteran Forum member Kianjin often says that Wikipedia is one of his favorite sources for information on stars. This link is a great introduction to the various types of variable stars we see here at Planet Hunters.

http://en.wikipedia.org/wiki/Variable_star

Another good site: http://www.aavso.org/vsots_archive

NASA Exoplanet Archive (NEA) periodogram Generator- Enter Kepler Star Identification (KID) number into program to run a periodogram.

http://nsted.ipac.caltech.edu/applications/ETSS/Kepler_index.html

Posting your periodogram on discussion page takes a couple of steps. First open an account on free site PhotoBucket to host your image. Right click on periodogram and save to your computer. Upload image to PhotoBucket. You most likely will need to re-size it on the site.

Copy and paste IMG code and paste into dialog section by clicking on picture icon top right of box. There is one slight trick though, you will have to remove [IMG ] on each side of your link as they will not be accepted in the URL box.

Look up Kepler Science papers here:

http://arxiv.org/find/astro-ph/1/au:+Uytterhoeven_K/0/1/0/all/0/1

Pdf files of science papers that are no cost.

Default_user
almost 8 years ago

You can also view the Kepler Planet Candidates as they would be shown on PH here

Default_user
almost 8 years ago

Thanks Tom. I will make this a featured discussion :-)

Default_user
almost 8 years ago

You are most welcome echo-lily-mai, happy to help out and thanks to all our PH seasoned members who took the time and effort to put these articles together and/or share important links/information for listed stars (Kianjin, EDG, Goryus, Paul Drye, Constovich, CTidwell3, Zoo3hans, Ggccg, ScottW, Nighthawk_black and many others).

Commonly Asked Questions

Here are some replies made by Meg on typical Light Curve questions by newer members to PH:

"mschwamb (science team)

Why are there large gaps in the light curve and more on how PH puts Quarterly LC graphs up?

http://talk.planethunters.org/objects/APH21094356/discussions/DPH100ia2h?per_page=10#4e7dae72686b983907004d31

"These gaps in the data are typically due to the Kepler spacecraft not observing. The gaps are caused by a few different things: Kepler went into safe mode and wasn’t taking data, the spacecraft was rotating towards the Earth to send the data back to NASA, the spacecraft has executing a roll (or quarterly roll as its called) to reorient its solar panels, or the data quality is bad typically due to a cosmic ray hit on the detector. "

What do Single low points (drops) in a light curve indicate?

http://talk.planethunters.org/objects/APH10667566/discussions/DPH100ia2i?per_page=10#4e7dbb9b686b9838f5004b96

http://talk.planethunters.org/objects/APH22120470/discussions/DPH100ia22?per_page=10#4e7db3a8686b9838f5004b3b

http://talk.planethunters.org/objects/APH21038821?per_page=10#4e7da717686b983907004cbb

"If you see single really low points, they're typically just a spurious detection - I usually try to see at least three points to call something a transit.

What are Planet Simulations and why are they put into the Light Curve data base here at Planet Hunters?

http://talk.planethunters.org/objects/APH10411007/discussions/DPH100ia2x?per_page=10#4e7e0d6d686b983907005248

What causes variability in the Light Curve?

http://talk.planethunters.org/objects/APH21106916/discussions/DPH100ia2s?per_page=10#4e7e00d6686b9839070050dc

http://talk.planethunters.org/objects/APH10272494?per_page=10#4e7da451686b9838f5004ad7

" I would say this is a pulsating star or a #pulsator where the changes in brightness you see in the light curve are from stellar variability likely due to internal pulsations of the star. I find pulsators hard to classify sometimes, because it looks like they might have lots of transits. But for this light curve I don't think there are any transits. "

Eclipsing Binaries in the Light Curves

http://talk.planethunters.org/objects/APH10325479/discussions/DPH100ia1x?per_page=10#4e7db42a686b9838f5004b49

More information on the Light Curves, Kepler and finding Planets

http://talk.planethunters.org/chat/discussions/DPH100ia0k#4e7da307686b983907004c99

Default_user
over 7 years ago

Updated Guide with some additional links to Kian's famous planetary calculator and Daryll's (Nighthawk_black) Kepler Open Cluster list to look for contamination from other stars. Also added in how to search at the International Variable Star Index (VSX).

Feel free to contact me (Tom128) by personal message if you want other helpful additions.

Default_user
over 7 years ago

Tom, you do such a great job with these helpful posts! Before we know it, Planet Hunters will have 500 PC's on the books. :))

Default_user
over 7 years ago

For my clarification, are all the light curves presented just 30 days? Is it possible to look at adjacent 30 day periods? If not how is it possible to detect variations that might have a period that falls outside the selection presented? (Sorry if this is covered somewhere else but I just started this and have not found the answer elsewhere.)

Default_user
over 7 years ago

You can use 'View Star' and 'Examine Star' to detect variations in different time periods (quarters) -- as long as the data is available, and also see comments others have made at that time. Hope that helps.

Default_user
over 7 years ago

The grey line (that appears under the points in some light graph) represent the error about the measure of that valor?

Default_user
over 7 years ago

What is a falsex sol? Should transits on falsex sol stars be ingnored?

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