[Atmob-discuss] [IOTAoccultations] RE: Eurynome occultation

Tue Nov 10 14:48:38 EST 2009

To reiterate, we did *NOT* use the NightShot mode to capture the
occultation.  

I'm wondering if selecting this mode changes (enables) CCD sensitivity
in the near IR?  While experimenting early on, the night shot mode
seemed to give a little more intensity on some stars, perhaps those that
are emitting in the near IR... I never got back to determining some IR
and non-IR stars to test more conclusively.  We should tape over the IR
LED so as not to "pollute" any NightShot images we take with stray
light.

Bruce and I determined that we were able to detect an 11th mag star in
normal camera mode, and 13th mag in the "Color Slow Shutter" mode that
we used, this while pointing within ~15-20 degrees of the moon.  Would
the same setup see fainter stars on a moonless night or in darker skies?
...gm

-----Original Message-----
From: Paul A. Valleli [mailto:valleli at rcn.com] 
Sent: Tuesday, November 10, 2009 12:41 PM
To: Glenn Meurer
Cc: Atmob-discuss at atmob.org
Subject: Re: [Atmob-discuss] [IOTAoccultations] RE: Eurynome occultation

Glenn,
I believe the Sony IR 'Nightshot' is doing little to gain faint images.
The 0 Lux is almost meaningless as it is dependent on wavelength and
they are using an IR LED to illuminate the foreground of the subject.
This lamp is probably blocked by the EP projection setup but might cause
scattered light in the FOV. 
In comparison to my Adirondack Stellacam 3, both have the same or
similar chips and similar near IR response but the Stellacam is far more
sensitive - 0.000001 LUX, due to better electronics. Most images are
quite grainy because of thermal noise. 
I called Adirondack about using the StellaCam for photometric use and
wondered if it used anti-blooming technology. They said it is in the
post-exposure processing, not on the chip, but useless for photometry
because the output data is only 8-bits. 24 or 32 bits are needed to get
any accuracy in an analysis program such as CCD Soft or Maxim DL. 
It looks like use could enhance the brightness and contrast with
software but it would have to be done frame-by-frame. Some advanced
video editing programs will do this automatically, saving hours of work.

Of course, with only a few seconds of eclipse, one would only be dealing
with less than 100 frames. The most important data, however, is the time
of ingress and egress and that requires an accurate time reference.

Paul   

---- Original message ----

Date: Mon, 9 Nov 2009 20:56:51 -0500
From: "Glenn Meurer" <glenn at entropian.com>
Subject: Re: [Atmob-discuss] [IOTAoccultations] RE:  Eurynome
occultation
To: "'Bruce Berger'"
<bruce at scopemaker.com>,<IOTAoccultations at yahoogroups.com>
Cc: marek at portents.com,Gary.Jacobson at CH2M.com,"'Discuss-Amateur
Telescope Makers of Boston'" <atmob-discuss at atmob.org>

Regarding questions raised locally of the mode of the 
TRV38 during our capture of 79 Eurynome pass, (and a little bit of 
confusion over he modes we could have been in):  
We 
captured the video using the "Color Slow Shutter" mode of the 
camera.

We 
don't know exactly what's happening inside the camera or what if any
signal 
processing might be happening post-image.  All I've found so far 
is from the manual:
With Sony's NightShotR infrared system, 
capture video in total darkness (0 lux) up to 10 feet away. Super
NightShot 0 
Lux recording mode automatically adjusts the shutter speed to increase
picture 
brightness and clarity. Color Slow Shutter mode allows you to record in
low 
light situations with full color detail by slowing down the shutter
speed. 

Shutter Speed : 1/4-1/4000 (Program AE 
Mode)  {This would seem to indicate slowest speed is 1/4 second, but the

image seemed to persist as a smear for much longer that this (up to ~2-3

seconds) when we slewed the scope, so possible the Color Slow Shutter
goes 
lower than 1/4 s.}

We 
might have gained a little more with the "Super NightShot", but I think
all this 
does is bias the CCD to accept photons in the near IR and slow down the
shutter 
the same as the Color Slow Shutter mode does.  The operative word here
is 
think, as again,  I haven't found a definitive source on the internal 
operations of the camcorder.  (I know the near IR behavior because it 
"sees" the IR signal from it's own remote control when in NightShot 
mode.

The 
chip in the camera is described thus:

1.0 Megapixel (Gross) Advanced HAD. CCD Imager

1/4.7" Advanced HAD (Hole Accumulation Diode) CCD 
imager with 690K (effective) pixels provides excellent detail and
clarity, with 
exceptional digital video performance (520 lines of horizontal
resolution). 
Realize great looking digital still images utilizing 1000K (effective)
pixels. 
The Megapixel technology enhances your digital videos and digital still 
photography performance. 

14-Bit DXP A/D Conversion

Minimum Illumination : 
7 Lux (0 Lux with NightShotR Infrared System) 
F : 
1.8-2.0 
Focal Distance : 3.7-37mm 

I think Bruce mentioned eyepiece projection 
somewhere, 40 mm Plossl attached to the camcorder by a filter-to-lens 
adapter.  (Images are vignetted).

Hope this clarifies a bit on the conditions of the 
capture.

...gm
Glenn 
Meurer

-----Original Message-----
From: 
atmob-discuss-bounces at atmob.org [mailto:atmob-discuss-bounces at atmob.org]
On 
Behalf Of Bruce Berger
Sent: Monday, November 09, 2009 1:48 
PM
To: IOTAoccultations at yahoogroups.com
Cc: 
<IOTAoccultations at yahoogroups.com>; Discuss-Amateur Telescope Makers of 
Boston
Subject: Re: [Atmob-discuss] [IOTAoccultations] RE: Eurynome 
occultation

I saw it, but without the right tools it was hard to quantify. David 
asked me to send the tape in for analysis. 

Bruce Berger

Bruce at Scopemaker.com

Check out my astronomy site-http://scopemaker.com/blog

Sent from my iPhone

On Nov 9, 2009, at 11:58 AM, Marek Kozubal <marek at portents.com> 
wrote:

Bruce. You have the same stepped disappearance I observed. Hard to 

tell if the reappearance is stepped as well...

Looks like we have 
a double star or something else interesting on 79...

-Marek

On 
Nov 9, 2009, at 11:04 AM, "Bruce Berger" <bruce at scopemaker.
<mailto:bruce%40scopemaker.com> com> 

wrote:

> Hi,
>
> I just added a video of the 
morning occultation by (79) Eurynome at 
> 05:47
> this morning 
to the website. Unfortunately the earlier video of 
> (694) 
Ekard
> was too dim be show correctly once I transferred it to the 
PC.
>
> Check it out at the URL below.
>
> Clear 
skies!
>
> Bruce Berger
>  <http://scopemaker.com/blog> http://scopemaker.com/blog
>
> 
-----Original Message-----
> From: atmob-discuss- <mailto:atmob-discuss-bounces%40atmob.org>
bounces at atmob.org
> 
[mailto:atmob-discuss- <mailto:atmob-discuss-bounces%40atmob.org>
bounces at atmob.org] 
On Behalf Of Bruce Berger
> Sent: Monday, November 09, 2009 4:52 
AM
> To: IOTAoccultations@ <mailto:IOTAoccultations%40yahoogroups.com>
yahoogroups.com
> 
Cc: Discuss-Amateur Telescope Makers of Boston; Gary.Jacobson@
<mailto:Gary.Jacobson%40CH2M.com> CH2M.com
> Subject: [Atmob-discuss] 
Eurynome occultation
>
> Woohoo! 2 in one night
>
> 
Glenn Meurer & I got it for 1+ seconds at atmob in 
westford!
>
> Bruce Berger
>
> Bruce at Scopemaker. <mailto:Bruce%40Scopemaker.com> com
> 
Check out my astronomy site-http:// <site-http://scopemaker.com/blog>
scopemaker.com/blog 
Sent from my 
> iPhone
> 
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> 

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