Transcript Exoplanet Detection with an 8” LX200 - Part 1

Exoplanet Detection with an 8” LX200 :
Part 1 : Preparation
The Aim
Flux (or Mag)
Position Now
Ingress
Mid Transit
Egress
Light from Host Star
Light from Control Star
UT Hours
David Richards
2007-October
All pictures in this presentation are
by the author (unless specifically indicated)
and were taken with 8” LX200 / ST7e
Exoplanet Challenge
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First exoplanet transit detection made in 1999 - HD 209458b
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Castellano et al (NASA Ames) demonstrated HD 209458b transit detection
with an 8” LX200 telescope and ST7e CCD camera
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JAAVSO, Vol 33, No 1, 2004
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Same equipment as me !
Same journal volume as a paper by D.Mais and myself on Mira variables !
Led to a strong ambition to detect an Exoplanet for myself
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14 more transiting exoplanets discovered 2004-2007
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It’s both feasible and now regularly proven that amateurs with CCD cameras and just
moderately sized telescopes can detect transit events
I’ve made my own exoplanet detection attempts in 2005 and 2006, but without
firm success
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HD 209458 (Osiris, 13 Pegasi )
Charbonneau et al 2000, Henry et al 2000 (from Hipparcos Images ?)
Requires ideal sky conditions and the highest possible precision (<0.005 m)
I’m currently optimising my imaging setup and (with luck) hope to make a firm
transit detection during the 2007/8 season.
Table of Nearby Transiting Exoplanets
(Jul 2007)
Discovery
Date
1999
2004
2005
2005
2006
2006
2006
2006
2006
2007
2007
2007
2007
2007
2007
Object
Name
HD 209458
TrES-1
HD 149026
HD 189733
HAT-P-1
TrES-2
WASP-1
WASP-2
XO-1
GJ486
HAT-P-2
HAT-P-3
TrES-3
XO-2
XO-3
Constellation
PEG
LYR
HER
VUL
LAC
DRA
AND
AND
CrB
HER
UMa
HER
LYN
V
Mag
7.65
11.79
8.15
7.67
10.4?
11.41
11.79
11.98
11.19
10.68
8.71
11.86
12.4?
11.18
9.80
Depth
[mag]
Length
[hr]
Period
[day]
0.017
0.026
0.003
0.025
0.016
0.017
0.011
0.020
0.023
0.008
0.006
0.014
0.026
0.015
0.009
2.98
2.45
3.20
1.74
2.70
1.70
1.40
1.78
2.96
0.80
3.46
2.10
1.34
2.70
2.70
3.52
3.03
2.88
2.22
4.47
2.47
2.52
2.15
3.94
2.64
5.63
2.90
1.31
2.62
3.19
Note : Most known transiting exoplanet sols are visible from N. Hemisphere )
5 distant exoplanets (OGLE-TR-10,56,111,113,132) in Sagittarius and Carina are not listed,
[OGLE - Optical Gravitional Lensing Experiment ]
My Own Equipment & Setup
Meade 8” LX200
Goto Telescope
ST-7e
CCD Camera
Equatorial
Wedge
Permanent
Pier
2005 Attempt – HD 209458
60s exp (C Filter)
Planet HD 209458b around HD 209458 (Osiris)
Discovered in 1999 (followed up 1999-2004)
Parent Sol is a +7.6 magnitude star in Pegasus
Orbital period 3.52 days. Transit duration ~ 3 hours,
Transit depth 0.0165 mag
Attempted Transit Observation in V Filters, 2005-08-08
Depth of magnitude
dip being looked for
15s exposures
(V Filter)
2006 Attempt – TrES-1
Planet TrES-1 around GSC 2652:1324
Jupiter sized planet discovered in 2003-2004 (R.Alonso et al)
Sol +11.8 magnitude star in Lyra (lying at ~ 500 ly distance)
Orbital period 3.03 days. Transit duration ~ 2.5 hours,
Transit depth 0.023 mag
Av 3 x 20s exp (C Filter)
Attempted Transit Observation in C Filters, 2006-08-08 / 09
30s exposures
(C Filter)
Mid Transit
(predicted)
End Transit
(predicted)
Depth of magnitude
dip being looked for
Improving my chances
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Transit Opportunities - Dates/Times /Airmass
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Baseline Images for each candidate
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Software that’s going to work on that one ideal night when conditions are perfect
Focus / FWHM monitoring
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Improved Polar Alignment (aiming for less than 1 arc min, current misalignment is 3.4 arc min )
Guiding between frames with new script that is robust to passing cloud
Robust Software / Procedures
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New power source installed in early 2007 has fixed previous problem with dew heater
Reduction in star drift / keep stars fixed on same pixels
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Not realistically feasible with current focuser, due to gravity droop on CCD camera
(option to invest in new heavy duty focuser, but avoiding at this stage)
Anti-Dew System
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Central Image Positions, Reference Stars, Exposure Times
Better Flat fields
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Screening worksheet/charts
Script to monitor FWHM / sky brightness in realtime
Better prediction of Clear Weather & Good Seeing
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Weather forecasts / Jet Stream monitoring
Screening Transit Opportunities
Screening Transit Opportunities
2007-09-26
HD 209458
Time (UT)
16:00 17:00 18:00 19:00 20:00 21:00 22:00 23:00
1.0
0:00
1:00
2:00
3:00
4:00
5:00
6:00
7:00
1.5
2.0
Airmass
2.5
3.0
3.5
4.0
4.5
5.0
Sunset/Sunrise
Civil Dusk/Dawn
Astron. Dusk/Dawn
Naut Dusk/Dawn
HD 209458
Egress
Transit
Ingress
HD 189733 – good candidate
in Vulpecula
mag +7.67, transit depth 0.025 mag
ref star mag +8.1
Results from guiding between frames
Practice Photometry
(non exoplanet star)
Total Cloud Cover Forecast
for Sun Sept 2nd, 23:00
(2 ½ days prior)
Weather
Total Cloud Cover on
Sun Sept 2nd, 23:00
(on the day forecast)
Latest Attempt : WASP-1
Transit Depth of magnitude
dip being looked for (0.011 m)
Pointing Accuracy during WASP-1
Transit Attempt, 2007-09-14
How close ?
Star
Mag
Transit
Depth
(mag)
HD 209458
Precision
needed
SN
needed
Attempt
(assume min 50% (assuming
of transit depth) error=1/SNR)
Exposure
SN
achieved
(sec, filter)
(min of Var &
Comp Star)
Potential
Min RMS
RMS in
Practice
7.65
0.017
0.009
120
2005-08-08
15s, V
220
0.005
0.01-0.02
TrES-1
11.79
0.026
0.013
80
2006-08-08
60s, V
80
0.013
~ 0.01 - 0.02
WASP-1
11.79
0.011
0.006
180
2007-09-14
60s, R
90
0.011
0.009-0.014
7.67
0.025
0.013
80
10s, V
160
0.006
no data
HD 189733
HD 209458 opportunity, 2007-11-18
HD 189733 opportunity, 2007-10-16