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My first "real" light curve

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13 years 9 months ago - 13 years 9 months ago #86669 by ayiomamitis
Replied by ayiomamitis on topic Re:My first
dmcdona wrote:

Anthony - I hadn't considered AIP4WIN. I'd be interested on your thoughts in terms of its perfromance for exoplanets - especially where you're well into the millimag zone.

Dave,

I am quite happy with AIP4Win and as indicated by its continued use at my end for the past few years. One criticism which I have heard on occasion, and which I do not know if it is true or not, is the possibility that it slightly underestimates the standard errors.

With my exoplanet work and using AIP4Win, I have been able to detect exoplanet transits with a relatively shallow depth.

It is my understanding that Maxim/DL also does differential photometry but it is something which I have not looked into.

As an aside and further to the earlier comment above, I always try and match my variable star to comparison and check stars which have the same spectral type, virtually the same magnitude and the same air mass coefficient so as to have the latter factor cancel out.

Anthony.

Anthony Ayiomamitis
Athens, Greece
www.perseus.gr
Last edit: 13 years 9 months ago by ayiomamitis.

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  • dmcdona
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13 years 9 months ago - 13 years 9 months ago #86678 by dmcdona
Replied by dmcdona on topic Re:My first
Atually Dave, I sent Gareth an email a few weeks back on a proposed categorisation system for describing the non-spherical attributes of asteroids.

He hasn't gotten back to me - yet. He's probably asking for further clarification from Dan Green or NASA or something.

In increasing order of non-sphericalness...

1. Onion
2. Potato (new - Cypriot or Egyptian)
3. Potato (old - e.g. Maris Piper)
4. Tomato (plum)
5. Swede
6. Turnip
7. Cabbage
8. Garlic
9. Potato (sweet)
10.Banana

Maybe it was item 10 that threw him - its not a vegetable...
Last edit: 13 years 9 months ago by dmcdona.

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13 years 9 months ago #86679 by michaeloconnell
Replied by michaeloconnell on topic Re:My first

Maybe it was item 10 that threw him - its not a vegetable...

Neither is a tomato Dave....

As for the potato-scale....sounds a little half-baked....

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13 years 9 months ago #86680 by dmcdona
Replied by dmcdona on topic Re:My first "real" light curve
Knowing Gareth well, I had already pre-empted the "tomato" question:

"The question of whether the tomato is a fruit or a vegetable found its way into the United States Supreme Court in 1893. The court ruled unanimously in Nix v. Hedden that a tomato is correctly identified as, and thus taxed as, a vegetable, for the purposes of the 1883 Tariff Act on imported produce. The court did acknowledge, however, that, botanically speaking, a tomato is a fruit."

In view of the stony silence from Haravrd, perhaps I should just just drop it - I'd hate to be accused of a breach of the peach.

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13 years 9 months ago #86684 by DaveGrennan
Replied by DaveGrennan on topic Re:My first
michaeloconnell wrote:

As for the potato-scale....sounds a little half-baked....


Ok can i just 'Chip' in here?:P

I'll get me coat:dry:

Regards and Clear Skies,

Dave.
J41 - Raheny Observatory.
www.webtreatz.com
Equipment List here

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13 years 9 months ago #86689 by eansbro
Replied by eansbro on topic Re:My first
Hi Dave Mc,

Mira is a powerful tool!
As the saying goes its only easy when you know how.

As long as you follow the instructions carefully it works.
It took me a while to grasp the methodology. It is complex, but that is my opinion.

Mira does handle both zero points and second order extinctions.
and also uses Landolt standard stars.

There are transformation equations to derive the zero point for each zero point obseration and then you average the zero points in each color to derive the nightly zero points. Zero points can change during the observing run if sky conditions vary. Therefore, if you are going to transform your data to standard Landolt magnitudes, you need to check periodically to make sure zero points haven't changed significantly. Mira has all those key elements. Basically you don't have to do any scripting.

A fast way to do this is to slew your telescope in order to pick north polar sequence stars east of the meridian (say 2 hours). The airmass through which they are observed changes very slowly and by small amounts. Therefore significant changes in extinction of these stars over a few hours, means that sky conditions are changing and you need to take new zero point measurements using another new group of Landolt standard stars near the meridian.


I have used MIRA over some years and have used it for photometry of exoplanets, but mainly for source extraction. This is important for detection and measurement of all objects brighter than a threshold value. I have applied this in research on very faint objects.

You probably know I have carried out a survey for outer planets in the outer solar system. Picked up 44 suspects. Source Extraction was applied to all these suspects because of there faintness. A very useful tool!

I hope that helps.

Eamonn

www.kingslandobservatory.com

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