2. White Dwarf WD 1145+017 Photometric Monitoring Observations by a Team of (Mostly) Amateur Observers
B. L. Gary, 2 of 4 web pages, Last updated 2016.12.19

1 of 4 - 2015.11.01 to 2016.01.21:   1st set of LCs for 2015/16 observing season 
2 of 4 - 2016.01.17 to 2016.07.13:   2nd set of LCs for 2015/16 observing season (you are here)
3 of 4 - 2015.11.01 to 2016.07.13:   Overview, Results & Model Speculations - based on all 158 LCs for 2015/16 observing season 
4 of 4 - 2016.10.25 to 2017.01.31:   1st set of LCs for 2016/17 observing season 

Status Update:  No recent updates.  

Links on this web page:
    List of observing sessions 
    Observing session observations   
    Finder image 
    References & related links  
    Download of LC data file for 2016.01.27 to 2016.07.17  

List of observing sessions   

2016.07.13 Gary/HAO  
2016.07.12 Gary/HAO  
2016.07.11 Gary/HAO  
2016.07.08 Gary/HAO  
2016.07.04 Gary/HAO  
2016.07.03 Gary/HAO  
2016.07.02 Gary/HAO  
2016.06.18 Gary/HAO  
2016.06.17 Gary/HAO   
2016.06.16 Gary/HAO  
2016.06.08 Gary/HAO  
2016.06.04 Gary/HAO  
2016.06.03 Gary/HAO  
2016.05.31 Gary/HAO  
2016.05.29 Gary/HAO  
2016.05.28 Gary/HAO  
2016.05.25 Kaye/Gary JBO  
2016.05.24 HAO Gary  
2016.05.22 Kaye/Gary JBO     
2016.05.21 Gary/HAO  
2016.05.20 Gary/HAO 
2016.05.12/13 Alonso IAC80  
2016.05.12 Kaye/Gary JBO  
2016.05.11 Kaye/Gary JBO  
2016.05.10 Kaye/Gary JBO  
2016.05.09 Kaye/Gary JBO  
2016.05.08 Kaye/Gary JBO  
2016.05.07 Kaye/Gary JBO  
2016.05.06/07 Hambsch  
2016.05.06 Kaye/Gary JBO  
2016.05.05 Kaye/Gary JBO  
2016.05.04/05 Hambsch  
2016.05.03/04 Hambsch   
2016.05.03 Kaye/Gary JBO   
2016.05.02/03 Hambsch   
2016.05.02 Kaye/Gary JBO 
2016.05.01/02 Hambsch 
2016.05.01 Kaye/Gary JBO 
2016.04.30/05.01 Hambsch  
2016.04.30 Gary/HAO  
2016.04.30 Kaye/Gary JBO 
2016.04.29/30 Hambsch  
2016.04.29 Gary/HAO  
2016.04.29 Kaye/Gary JBO 
2016.04.28/29 Alonso/IAC80 
2016.04.28 Gary/HAO 
2016.04.28 Kaye/Gary JBO 
2016.04.28 Benni 
2016.04.27/28 Hambsch
2016.04.27/28 Alonso/IAC80 
2016.04.27 Kaye/Gary JBO  
2016.04.26/27 Alonso/IAC80  
2016.04.26 Kaye/Gary JBO 
2016.04.25/26 Alonso/ IAC80  
2016.04.25 Gary/HAO
2016.04.24/25 Alonso/IAC80  
2016.04.24 Gary/HAO
2016.04.23/24 Alonso/IAC80  
2016.04.23 Gary/HAO 
2016.04.22/23 Hambsch 
2016.04.22/23 Alondo  
2016.04.22 Gary  
2016.04.21 Gary HAO 
2016.04.16 Gary HAO 
2016.04.13 Gary HAO 
2016.04.09 Gary HAO 
2016.04.06 Hambsch 
2016.04.06 Ogmen 
2016.04.03 Gary HAO  
2016.04.01/02 Gary & Ogmen  Combined LC for 4 orbits (Ogmen & Gary)
2016.04.02 Gary HAO  
2016.03.27 Gary HAO  
2016.03.20 Gary HAO  
2016.03.18/19 Alonso IAC80  
2016.03.18 Gary HAO  
2016.03.15 Gary HAO  B- & R-band depth ratio
2016.03.13 Gary HAO  
2016.03.10 Gary HAO  
2016.03.09 Gary HAO  
2016.03.03 Gary HAO  
2016.03.02 Gary HAO  
2016.03.01 Gary HAO 
2016.02.29/03.01 Alonso IAC80  
2016.02.29 Gary HAO  
2016.02.29 Alonso IAC80  
2016.02.28 Gary HAO  
2016.02.27 Gary HAO  
2016.02.22 Gary HAO  Full moon ruined data
2016.02.18 Gary HAO  
2016.02.16 Gary HAO  
2016.02.15 Alonso IAC80  
2016.02.14 Alonso IAC80  
2016.02.12 Gary HAO   
2016.02.12 Alonso IAC80  
2016.02.10 Gary HAO    
2016.02.09 Gary HAO  B & V differential photometry
2016.02.07 Gary HAO 
2016.02.05 Gary HAO 
2016.02.03 Gary HAO 
2016.02.03 Alonso IAC80  
2016.01.31 Alonso IAC80  
2016.01.30 Gary HAO   
2016.01.27 Gary HAO
2016.01.24 Alonso IAC80  
2016.01.23 Alonso IAC80  
2016.01.19 Alonso IAC80  
2016.01.18 Alonso IAC80  
2016.01.17 Alonso IAC80 

Note: The average depth during K2 was ~ 1.3% (30-minute exposure times), with a range of 0.7 to 2.3%. The K2 simulated depth from observations during the past 4 months reached a maximum of ~ 25% in early December, decreased to 8% in February, and has recently risen to 35%. However, the present peak of K2 depth is due to all 6 dips occurring at the same phase; most of an orbit is devoid of dips, which is quite a contrast with December.

Observing Sessions  


2016.07.13 Gary/HAO  







2016.07.12 Gary/HAO  

The moon was 24 deg away and "seeing" was worse than usual. I observed to airmass 4.5, which is normally unwise, especially with a blue target, but I'm "desperate" to get phase coverage.





2016.07.11 Gary/HAO  

Observing sessions are limited to 1.3 hours, so 3 or 4 consecutive sessions have to combined to provide complete phase coverage. Based on the weather forecast, Jul 11 will be the first of 4 such sessions.





2016.07.08 Gary/HAO  





2016.07.04  Gary/HAO  

This is a combination of 3 observing sessions, needed to achieve complete orbit phase coverage.







2016.07.03  Gary/ HAO  



2016.07.02  Gary/HAO  

Observing sessions are limited to ~ 1.8 hours now, so it takes 3 or 4 sessions to get complete orbit phase coverage. This is the first of such a series.



2016.06.18 Gary/HAO  









2016.06.17 Gary/HAO  

It now requires two consecutive nights to provide complete phase coverage. Here's my Jun 16 & 17 LCs' combined.









2016.06.16 Gary/HAO  

Bibbous moon was nearby, but I wanted to know if any new activity was occurring. None was during the 2.8 hrs that included the "main group" of dips (G6121).





2016.06.08 Gary/HAO  

The longest observing session for my latitude is 3.9 hrs, and getting shorter by ~ 4 minutes each day. Two nights in a row provides complete phase coverage.







2016.06.04 Gary/HAO  

I observed just to see if the activity level was continuing to decrease; and it was!









2016.06.03 Gary/HAO  

Not a completeorbit, but enough to show that the main group (G6121) is fading & there's no evidence for the b dip.







2016.05.31 Gary/HAO   









2016.05.29 Gary/HAO  









2016.05.28 Gary/HAO  









2016.05.25 Kaye/Gary JBO  









2016.05.24 Gary  

 







2016.05.22 Kaye/Gary  

Couds, wind and full moon ruined most of the observing session, but we got a 1-hr segment that sampled the main group of dips.



2016.05.21 Gary/HBO  

It was windy, and there was a full moon (52 deg away), but I observed anyway.

  







2016.05.20 Gary/HBO  





2016.05.12/13 Alonso/Palle IAC80  

 







2016.05.12 Kaye/Gary JBO  

 







2016.05.11 Kaye/Gary JBO  


 







2016.05.10 Kaye/Gary JBO 


   
 





2016.05.09 Kaye/Gary JBO  

   







2016.05.08 Kaye/Gary JBO 

 







2016.05.07 Kaye/Gary JBO  

 




Note, since cadence is 36 seconds (25-sec exposures) more short-term structure is possible to be recorded than for the other LCs (with ~70-sec cadence, for example).




2016.05.06/07 Hambsch  

Data archived but not yet processed.


2016.05.06 Kaye/Gary JBO  


   







2016.05.05 Kaye/Gary JBO  

    


Combination LC. The B dip moved between the orbit observed by Hambsch & Kaye/Gary.





2016.05.04/05 Hambsch 

It was cloudy so the noise level is high.

      


Combination LC. The B dip moved between the orbit observed by Hambsch & Kaye/Gary.



2016.05.03/04 Hambsch  

  







2016.05.03 Kaye/Gary JBO  

  







2016.05.02/03 Hamsch   

Data archived but not yet processed.


2016.05.02 Kaye/Gary JBO  

This is our "best ever" JBO LC. The benchmark of 10-min SE was 8.2 mmag, with cadence of 39 seconds.








2016.05.12/02 Hambsch 





2016.05.01 Kaye/Gary JBO  

For the past 2 observing sessions measurement has been the same, at 9.1 mmag per 10-minute interval. The individual image noise level of 37 mmag is for 25-second exposures. The cadence is 39 seconds (14 sec download and overhead time, duty cycle = 64%). Clouds ruined ~ 1 hour of data in the middle of the observing session.







2016.04.30/05.01 Hambsch  

Data archived, not yet reduced.


2016.04.30  Gary/HAO  









2016.04.30 Kaye/JBO  

JBO observing setting changed: 1) sub-frame imaging (75%), 2) exposure time reduced to 25 sec, 3) plate-solving every 40th image, 4) no focusing after start of observing session. The goal is to improve both temporal resolution and duty cycle. The 10-minute SE did improve by the expected amount (13 mmag to 9 mmag). Because this observing session didn't include a complete orbit I won't create a K2sim plot or add the dip model to the waterfall plot.








2016.04.29/30 Hambsch  

Data archived, not yet reduced.


2016.04.29 Gary/HAO  

Data archived, not yet reduced.


2016.04.29 Kaye/JBO  

  








2016.04.28/29 IAC80  

  








2016.04.28 Gary 

Data archived, not yet reduced.


2016.04.28 Kaye/JBO 

Clouds ruined several hours before useable data could be obtained, starting at 6.7 UT.



2016.04.28 Benni

Clouds rendered data too noisy to use.


2016.04.27/28 Hambsch  









2016.04.27/28 IAC80  

Clouds interfered with when data could be obstained, and they probably affected the noise level for part of the LC.







2016.04.27 Kaye/JBO  

Data archived, not yet reduced.


2016.04.26/27 IAC80  

   





2016.04.26 Kaye JBO 

Windy, but still good data. 30-sec exposures.

    







2016.04.25/26 IAC80 Alonso & Palle 

Discovery of new dip (after the double dips). 60-sec exposures.







2016.04.25 Gary  

Winds made seeing bad; apparently there were occasional cirrus.

   






2016.04.24/25 IAC80  









2016.04.24 Gary  

  





2016.04.23/24 IAC80  Alonso & Palle 










2016.04.23 Gary 

Normally I wouldn't observe with overcast cirrus and a full moon (45 deg away), but I was desperate to know what changes were occurring at WD1145. RMS was ~ 3 times worse than usual (112 mmag vs 34 mmag per image), due to cirruse with an optical depth that varied from 0.0 to 1.5, typically ~ 0.5).

  





2016.04.22/23 Hambsch  





2016.04.22/23 Alonso & Palle  

    







2016.04.22 Gary 

Full moon 35 deg away, persistent cirrus, causing noise level (per image) to be higher than normal by factor 3 (114 mmag vs. 34 mmag per image).

 
  





2016.04.21 Gary

I was desperate to learn if activity level was increasing as the tight group of fragments pass the asteroid, so I observed in spite of the fact that a full moon was 23 deg away and my sky had thin cirrus. SNR was in fact quite bad, as individual images exhibited RMS that was ~ 5 times greater than normal (173 mmag vs 34 mmag). Nevertheless, the LC appears to be usable, and does in fact show the expected increased activity!

  






2016.04.16 Gary

Observing conditions were pretty bad: wind & gibbous moon 37 deg away; RMS > twice normal (77 mmag vs. 34 mmag).

   





2016.04.13 Gary 

     







2016.04.09 Gary  







2016.04.06 Hambsch (Belgium)



2016.04.06  Ogmen (Cyprus)





2016.04.03  











The model is from one day earlier, which allows changes in 1 day to be quite apparent.




2016.04.01/02 (Ogmen) & 2016.04.02 (Gary), 18-hour LC

Starting on this date I'll switch to use of a "fragment ephemeris" - with zero phase defined by P = 4.4916 hrs and a JD reference of 2457480.8083 (2016 Apr 02, 07.4 UT). For a few dates I'll follow the phase-folded LC using the fragment ephemeris with the previously adopted A-period (asteroid) ephemeris.



Combining the Ogmen and Gary LC data produces a LC from 2016.04.01 17.6 UT to 201604.02 11.5 UT (17.9 hours, with a data gap of 3.8 hrs; nothing was happening during this gap). Before showing the combined LC, let's compare the Ogmen model fit (orbits #1 & #2) with later data (orbits #3 & #4).


Gary data with Ogmen model fit, showing change during a 9-hour interval. The Ogmen model fit is for data for orbits #1 & #2; the Gary data is for orbits #3 and #4.

Another way to show the difference is to plot both data sets on the same phase-folded LC.



But a better way to compare is to show the entire LC of both data sets (including only the parts near the dip structure):



Or, let's just show the UT regions containing the dip structure:



This last figure shows a systematic change of dip depth during the last 1/2 of the dip structure. There is also a suggestion of the early and sharp dips moving to earlier times. 

To my knowledge this is the first LC sequence of dip patterns for four consecutive orbits.


2016.04.02  

The data in this section is compared with data by Ogmen, taken during the previous two orbits. The combined and comparison analysis is shown in the preceding section.




Folding my data (orbit #3 &4) and model fitting.



2016.04.01/02  Yenal Ogmen

Starting with this date I will include observations from other observers who collaborate with me in producing combine, long light curves for the purpose of assessing changes of fade shape and depth on timescales of an orbit. The following is LC data by Yenal Ogmen (Cyprus), showing a fade group for two orbits, which I'll refer to as orbit #1 and orbit #2. These data are combined with my observations of orbit #3 and #4 (above section).


Combining all data (orbit #1 & #2) with one model fit.



2016.03.27  

On this date we attempted a 4-observer LC, but only 2 observers were able to produce a LC segment. The goal was to detect dip depth changes during a 3-orbit combined LC. Roberto Zambelli (Italy, 16") obtained a LC showing the first fade and I obtained a longer LC showing the next two fades. Below is one fade model (average fit to my two fade patterns) shifted to 3 UT times using 4.5 hour shift intervals. Measurement precision is insufficient for assessing the presence of any actual fade structure changes. This project needs larger aperture telescopes with greater SNR.










2016.03.20  










2016.03.18/19 Alonso IAC80  









2016.03.18 Gary HAO     









2016.03.18/19 Alonso IAC80  




2016.03.15 Gary HAO    




2016.03.13 




Uses A-fragment ephemeris.


Uses A-asteroid fragment.






2016.03.10  









2016.03.09  









2016.03.03 

Another 9-hour observing session; processing underway...









2016.03.02  

This is one of the lowest activity LCs since observing began 4 months ago. There are no fade events near A-period zero phase, so apparently no new fragments are being generated. The only set of fade events are bunched together and given their drift rate (with respect to the asteroid A-period) they have to be at least 2.0 months old (generated in late January).









2016.03.01  










2016.02.29/03.01 Alonso IAC80  









2016.02.29 Gary HAO  










2016.02.28 Gary HAO   

The gibbous moon was 43 deg trailing, so wasn't a problem.










2016.02.27  

Gibbous moon rises ~ 30 deg after target.









2016.02.22 

Full moon was 30 deg ahead of target, which rendered LC too noisy to be useful.

2016.02.18  










2016.02.16  




Uses A-fragment ephemeris.


Uses A-asteroid ephemeris.






2016.02.15 Alonso IAC80  









2016.02.14 Alonso IAC80  









2016.02.12  









2016.02.12 Alonso IAC80  









2016.02.10










2016 Feb 09  

This night was devoted to measuring B-mag and V-mag using differential photometry of 12 nearby stars with APASS mag's. About half the images were made with each filter.





The measured mag's are: B = 17.174 0.030 and V = 17.250 0.019. Therefore, B-V = - 0.076 0.036.


2016 Feb 07

Cirrus was present for the entire observing session.









2016 Feb 05  

Observing conditions were good for this 8.3-hr session.


The K2sim way for assessing "fade activity level" continues to decline with date.


This is how that past several LCs "stack up."


Using A-fragment ephemeris (G6121 group).


Provisional phase-fold fit. Fade #1 is indeed drifting to the left (i.e., in "inner orbit").


Crude fade fit.


Crude fade fit.

2016 Feb 03

Under cold but clear skies, an 8.2-hr observing session produced a LC 1.8 orbits long.





Using the G6121 ephemeris.


Using the A-asteroid ephemeris. The sharp fade at UT' = 10.97 is "new."




1.8 orbits, showing fade activity confined to a 1.3-hr region (probably the zero phase region).

As a curiosity, Saul wondered if it was possible to estimate the period, and therefore "drift rate", of the sharp fade feature from the two appearances of it in one observing session. Answer: Yes!



The interval between the two sharp dips is 4.4950 0.0009 hrs, using chi-sqr minimization. This is compatible with the Dec/Jan drift rates for 15 fade features, corresponding to P = 4.4925
hrs (with a dispersion of 0.0019 hrs). This P is within the range found for the 15 drifters (P = 4.4905 to 4.4951 hrs), and statistically different from the A-period drift rate (4.4989 0.0001 hrs, dP = 0.0049 0.0009, or 5.4-sigma). So it's possible during one observing session to learn whether a fade feature is free of the source asteroid and orbiting the WD in an "inner orbit" vs. still close to the L1 point and not yet drifting free.

2016.02.03 Alonso IAC80  





2016.01.31 Alonso IAC80  









2016.01.30 Gary HAO

A gibbous moon was ~ 24 deg away, which reduced SNR, but I observed anyway.


K2 would have measured a depth of 16%, which is slightly less than just 3 days ago (22%).


Using G6121 ephemeris.


The observing session ended sooner than planned, due to my mistake (requested too few images), but phase coverage is almost complete. Note that all but one fade is located within a 0.7-hr interval near phase zero. Fade depths < 10% would not be detected using this data.


The fade model is just approximate.


An approximate fade model.


2015.01.27

The full moon (90% illuminated) was 12 deg away, so SNR is quite a bit worse than usual; I felt "lucky" so I observed against my better judgement.

 
Phase is defined by the ephemeris (given above). K2 would have observed a 22% fade at zero phase for this ephemeris.


Using G6121 ephemeris.


Using A-asteroid ephemeris. Note that the deepest fades are at zero phase (when the asteroid source for the dust-emitting fragments is close to transit).






2016.01.24 Alonso IAC80  





2016.01.23 Alonso IAC80  







2016.01.19 Alonso IAC80 









2016.01.18 Alonso IAC80  





2016.01.17 Alonso IAC80  






The Poet Within Me

When a neighbor asked what Ive been doing lately, the poet within me spoke up: Ive been getting a far-future glimpse of our sun, the Earth and the matter that makes up you and me. I told how our sun will swell to giant size, then collapse into a white-hot dwarf star the size of Earth, followed by surviving planets disintegrating, breaking off pieces, some of which will include the atoms that once were you and me, and that we will in this way contribute to dust clouds that will obscure some of our diminutive sun's light, to be noticed by some intelligent observer elsewhere in the galaxy, curious to understand what's out there, and perchance to better know their future. I presume that those observers will be as clueless about the privileged time of their race as ours was while living through the best of times for us during the mid-20th Century on this wondrous home planet. At our human high noon, when our fortunate species prospered and squabbled upon a giving Earth, we forgot to feel gratitude. Yes, gratitude was the real subject for what I had been doing lately; it always comes when the grateful thing is gone, as it certainly will be when our horrible human race, with its deep-rooted tribal mentality, transforms an artisan created civilization into a cancer that chokes off most life on Mother Earth, eventually including itself. My neighbor politely nodded, pretending to understood.

Culture of Astronomy and the State of Pro/Am Collaborations

It has taken me about a decade to figure out that the astronomy culture of today has changed from what I knew ~ 5 decades ago, when I was a professional radio astronomer.

During the 1960s and 70s the culture was collegial; astronomers helped each other get established, and establishing a career required only a +2-sigma IQ and a love of the subject. We helped each other, and shared what we were doing without suspicion. During the 70s I transitioned into the atmospheric sciences, and lost track of the culture of astronomy, except for occasional grumblings by former colleagues. I recall MJ complaining, during the 1980s, that getting funded required being part of an "old boy's club."

After retiring in 1998 I remembered the fun of my childhood astronomy hobby, before college, so I bought a 10" Meade telescope and returned to astronomy as a hobbyist, an amateur. The transition from film to CCD was occurring, and as a result new observing opportunities for amateurs were opening up. I became one of the first amateurs to measure an exoplanet transit in 2002. I urged other amateurs to join in this fun, and created a web page for archiving amateur exoplanet transit LCs (AXA, with ~640 LCs). I tutored many of these amateurs so they could produce scientifically useful light curves. A few professional astronomers took note, and I was invited to collaborate by observing exoplanet candidate stars (the XO Project). Later I began a consulting arrangement with Vanderbilt University (i.e., KELT), lasting ~ 3 years.

I slowly started to take a new reading of the professional astronomy culture. It seemed that the most striking change was an out-of-balance supply/demand ratio; in other words,
there were too many young PhD astronomers competing for the funding available from NASA and NSF. It occurred to me that universities were graduating too many PhD astronomers because it allowed them to maintain teaching staff.

After a couple years consulting for an asteroid astronomer, I gained some insight into the funding atmosphere for that discipline. That's where I learned about the new need for sharp elbows, keeping secrets and bitter competition for recognition. More recently I learned something from working with a young WD astronomer, in which my role was creating a group of amateurs for providing all the observations.

I have come to realize the role of secrecy in creating a career in astronomy. Using others without their knowing it is also helpful. Accepting co-authorship without contributing is acceptable. Anything, in short, that promotes securing employment defines the new astronomy culture. I'm not overlooking the role of intelligence and knowledge; it's just that those are merely a minimum requirement. Having a +3-sigma IQ, and being highly motivated, are just the entry ticket for achieving a career in astronomy because those other new skills that I've recently learned about have become important. I sense the loss of "spontaneous fun" within this new culture, so it may now be secondary. And there's also a loss of trust. It is now necessary to think twice about a colleague's motives. For example, does that person have an affiliation with another group of astronomers doing work that competes with what we're doing together, and is he passing secrets. Who is going to beat us in publishing similar work, knowing from an informant our publishing schedule.

For some people, this may be fun; but not me! I'm old fashioned, and accustomed to openness and trusting relationships. If this is unfeasible, then count me out. I'll restrict my future collaborations to other amateurs. For this reason I am proud to be an amateur again!

The rest of what I originally wrote for this section might be considered a "rant" that's a bit too truthfully ugly for this web page. If anyone wants to read it you'll have to ask me for the web page PW. The username is "123" but to get the PW you'll have to e-mail me (see bottom of this page). The rant is located at link.

Finder Image


WD1145 is at 11:48:33.59 +01:28:59.3 (J2000). FOV = 27 x 18 'arc, northeast at upper left.

References

    Vanderburg et al, 2015, "A Disintegrating Minor Planet Transiting a White Dwarf," Nature, 2015 Oct 22, arXiv:1510.063387
    Croll et al, 2105, "Multiwavelength Transit Observations of the Candidate Disintegrating Planetesimal Orbiting WD 1145+017," ApJ, arXiv:1510.06434 
    Gaensicke et al, 2015, "High-Speed Photometry of the Disintegrating Planetesimal at WD 1145+017: Evidence for Rapid Dynamical Evolution," arXiv :1512.09150
    Rappaport et al, 2016, "Drifting Asteroid Fragments Around WD 1145+017," MNRAS, arXiv:1602.00740
    Alonso, R., S. Rappaport, H. J. Deeg and E. Palle, 2016, "Gray Transits of WD 1145+017 Over the Visible Band," Astron. & Astrophys., arXiv:1603.08823
    Petit, J.-M and M. Henon, 1986, Icarus, 66, 536-555 (link)

Related Links  
    WD1145 LCs for 2015.11.08 to 2015.01.21 on web page created for collaboration leading to paper by Rappaport, Gary, Kaye, Vanderburg, Croll, Benni & Foote:  link
    Some observing "good practices" for amateurs (book): Exoplanet Observing for Amateurs
    Hereford Arizona Observatory (HAO):  http://www.brucegary.net/HAO/
    Tutorial for faint object observing techniques using amateur hardware: http://brucegary.net/asteroids/  
    Master list of my web pages & Resume

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WebMaster: B. Gary Nothing on this web page is copyrighted. This site opened:  2016 Jan 27