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Read Noise and Gain - August 8, 2018

Recently I have taken it upon myself to learn (try to learn) Python and start to manipulate FITs images. My first "goal" was to write a program to calculate the read noise and gain of a detector using two biases and two flats. This is a standard method based on the relations below.

Gain = ((mean(Flat1)  +  mean(Flat2) - (mean(Bias1)  +  mean(Bias2))  /   (STD(Flat1-Flat2)^2 - STD(Bias1-Bias2)^2)

ReadNoise = Gain *STD(Bias1-Bias2)/sqrt(2)

So in addition to the 4 files of bias1.fit, bias2.fit,flat1.fit, and flat2.fit - you need to create a difference image (subtract from each other) for both the bias pair and the flat pair. This can all by done manually (I demonstrate this in a CCDStack tutorial I made long ago)- but with a little piece of code it is all quick and easy. The Gain and readnoise of your camera can be useful to know for a number of calculations. Here are the requirements:

1. Name the files exactly as I show above. Bias1.fit, Bias2.fit, Flat1.fit, Flat2.fit

2. Put files in the same directory you run the python program from. 

3. Run the code below. Note, you will need to have astropy installed in your python environment. It is what reads the FITs data into a numpy array... which makes life easy. 

This kind of thing might not be useful to non-programmers- but it is somewhat interesting to see the different ways problems are handled. Perhaps there are some Python people out there- if so, please let me know if I made an error! (I am a total newbie!) The code is below.


#!python
#
#Usage:
#  Learning Numpy stuff
#  Given two bias files named bias1.fit and bias2.fit as well as
#  two flat files named flat1.fit and flat2.fit
#  this program computes the Gain and Readnoise of the CCD camera

import numpy as np
import math
from astropy.io import fits

def main():
     #It is assumed the data is unsigned integers- hence the casting as float64 after reading in to array)
     bias1 = fits.getdata('bias1.fit')
     bias2 = fits.getdata('bias2.fit') 
     bias1 = bias1.astype(np.float64)
     bias2 = bias2.astype(np.float64)
     flat1 = fits.getdata('flat1.fit')
     flat2 = fits.getdata('flat2.fit')
     flat1 = flat1.astype(np.float64)
     flat2 = flat2.astype(np.float64)
     
     mean_flat1 = flat1.mean()
     mean_flat2 = flat2.mean()
     mean_bias1 = bias1.mean()
     mean_bias2 = bias2.mean()
     bias_diff =  np.subtract(bias1, bias2)
     flat_diff  = flat1 - flat2
     
     Gain = ((mean_flat1 + mean_flat2) - (mean_bias1 + mean_bias2))/((flat_diff.std())**2 - (bias_diff.std())**2)
     Readnoise = (Gain * bias_diff.std()) / math.sqrt(2)
     
     print("\nThe Mean value of Flat1 is %.2f ADU and Flat2 is %.2f ADU .\n" % (mean_flat1,mean_flat2))
     print("The Mean value of Bias1 is %.2f ADU and Bias2 is %.2f ADU .\n" % (mean_bias1,mean_bias2))
     print("The standard deviation of the Flat difference image is %.2f .\n" % flat_diff.std())
     print("The standard deviation of the Bias difference image is %.2f .\n" % bias_diff.std())
     print("The Gain for this camera given these files is %.2f electrons per ADU.\n" % Gain)
     print("The Readnoise is %.2f .\n" % Readnoise)
     

# This is the standard boilerplate that calls the main() function.
if __name__ == '__main__':
  main()
 

-Adam




                                               



Processing Relevations - March 19, 2018

NGC 2440:

 

Recently I completed processing an image of the small and famous planetary nebula NGC 2440. I worked on this object long ago (2003) using a 0.5m RCOS telescope at Kitt Peak. By today's standards the "normal" total exposure back then was easily 1/10th of what is typically done today. In addition new processing algorithms and techniques permit dramatically different kinds of presentations than what was done 10-15 years ago. These two things taken together- longer exposure times and effective non-linear treatment of bright objects (like NGC 2440) *strikingly revealed* something about this object that never "popped out" visually to me before. 

 

Specifically in this case I did a number of processing things for this data. First I upsampled the image by 2 in order to better see the small structures and deconvolve them with a bit more control. It is better to upsample, deconvolve, and then downsample if necessary- than it is to deconvolve and then upsample to make a larger picture. Keep in mind- this isn't drizzling the data. The data I was working with was already oversampled.

 

In addition I applied strong non-linear adjustments in Pixinsight including HDRMT on the (synthetic) luminance of the image and ArcSinhStretch and Masked Stretch on the RGB components. This resulted in the image below. After staring at it for a few moments I noticed the faint circular halo (which I had not seen before). This was simply the result of the long exposure time. In addition the inner structure clearly took the form of a bi-polar outflow! When this nebula is displayed with its natural brightness profile this structure is very hard to see- but by applying the non-linear adjustments the pattern recognition part of my mind was instantly struck by the shape. I thought this has to be something interesting.

 

Sure enough in a few moments I found papers by professional astronomers who noted the same thing and quantified the structures by measuring (spectroscopically) the velocities of the gas in different parts of the nebula and modeled the result. The image below notes three outflows as can be seen by my ouline on the left. It is the hour-glass shape in yellow-orange that first captured my attention. I just had never noticed it- not even in HST images. But it is very clear in this kind of representation! The paper from 1998 appears to be the first reference to these outflows. It is likely these bi-polar flows are caused by a system of binary stars and the episodic events change in their axial orientation as the pair rotates. Later in 2014 other astronomers wrote a paper that models the likely 3-dimensional shape of NGC 2440. 

The delightful aside I had when working on this image all came about with new tools and techniques. So next time you are working on your own data- be certain to have a critical eye for what is there and perhaps revealed by different processing choices- the discovery is great fun.

-Adam Block




                                               



Blood Moon Jan 31 2018 - January 31, 2018

Taken by: Linda Sinkay and Jim Goodenough in Freestone CA

 

Equipment/Settings:

Canon 6D MKII DSLR
In prime focus using a modified very low profile helical focuser
Orion 12" Reflector (1500mm focal length, F4.9)
1 second exposure
ISO 1600




                                               



Star Removal (Fabian Neyer Method) - January 20, 2018

Hi,

This is something of a follow-up to Fabian's excellent presentation of his technique of star removal. This method attempts to remove not only the stars from images- but also scattered starlight from their halos. Although somewhat involved/complex- it is a fascinating look into the kind of thing professional astronomers do as well as the cleverness of AIC star presenters such as Fabian. 

A two part video goes through the basic steps. There are a few errors... but the overall technique is demonstrated. A future video (perhaps) will show what to do with challenging data and stars. 

 

https://youtu.be/1rEBbZhsDIU

and

https://www.youtube.com/watch?v=nD-JhXikmRE

 

PixInsight is used for this tutorial. 

 

Happy New Year to all!

 




                                               



Final AIC 2017 Workshop Videos Now Online - January 17, 2018

The final workshop recordings from AIC 2017 are now online at the AIC Digital Library.

 

Included are:

  • Narrowband Filter & Image Processing in Photoshop  with Dr. Don Goldman and
  • Astro Processing With Photoshop and Lightroom with  Kerry-Ann Lecky Hepburn

 

These videos add over 3 more hours of recorded instruction from the 2017 meeting.




                                               



6 More AIC 2017 Workshop Recordings now online - January 12, 2018

Happy 2018!

 

Six new workshop videos recorded live at AIC 2017 are now available from the AIC Digital Library.  Combined, these latest recordings add over 6 additional hours of expert astrophotography advice.

 

Included in this update are:

  • High Resolution Lunar Imaging with Modest Equipment with Robert Reeves
  • Ethics in Astronomical Imaging with Richard Wright
  • Precision Focusing for Astrophotography with Dr. John Hayes
  • Astrophotography Milky Way Fusion with David Lane
  • Things I Learned in Pixinsight with Adam Block
  • Inside PixInsight- Workshop #2 with Dr. Ron Breecher and Warren Keller



                                               



3 Hours of New AIC 2017 Video Now Available - December 12, 2017

Over three additional hours of AIC 2017 Workshop videos are now available in the AIC Digital Library.

 

This new content includes:

  • Wide Field and TWAN imaging featuring Rogelio Bernal Andreo
  • Secrets of Deep-Sky Imaging with a DSLR featuring Jerry Lodriguss

 

Every week we will continue adding two new AIC 2017 Workshop recordings until all are available.




                                               



More AIC 2017 Videos are available - December 5, 2017

Two more AIC 2017 Workshop recordings were added to the AIC Digital Library this week:

  • Capturing the Moving Sky by Alan Dyer
  • Limiting Thresholds in Astronomical Imaging by Chris Hendren

 

Now, 6 AIC 2017 workshop videos with almost 10 hours of content are available for you to view at your convenience!

 

More will be added each week.




                                               



4 AIC 2017 Workshop Videos Now Available - November 29, 2017

The first four AIC 2017 Workshop videos are now available in the AIC Digital Library!

 

Every week, additional videos will be added until recordings of each AIC 2017 Workshop is accessible.

 

The first videos include:

  • Dr. Gaston Baudat- Imaging Under Seeing Limitation Conditions
  • Dr. Ron Breecher and Warren Keller- Inside PixInsight- Workshop #1
  • Tony Hallas- Turning Your Image into Something Special
  • Emil Kraaikamp- Planetary Imaging from A to Z using AutoStakkert!

 

These recordings total almost 7 hours of instruction from some of the world's finest astrophotography enthusiasts!

 

These videos are only available to AIC 2017 attendees and AIC Digital Library subscribers.




                                               



AIC 2017 Image Gallery Is Open - October 22, 2017

AIC 2017 Image Gallery

AIC 2017 Image Gallery is Open!

 

Prior to AIC 2017, attendees were invited to submit their best images so they could be viewed throughout the conference and, following that, on the AIC web site.  Now, over 150 of the most remarkable deep space, planetary, cometary, solar, lunar and TWAN-Syle images are available for your review at the permanent AIC 2017 Image Gallery




                                               



Exciting and Fullfilling - AIC 2017 - October 7, 2017

I enjoyed every minute of my second AIC Conference.  As a newcomer in 2015, I was amazed at all the resources and chances to learn new techniques.

 

In the space of 2 years, I realized now how many friends and contacts I'd acquired.

 

The 2017 Conference gave me more perspective as to the possibilities and some limitations on my astrophotography expectations.  As you listen in the sessions and learn, it is clear that ALL of the conditions, equipment and techniques matter when one strives for the ultimate astrophoto.

 

In my coastal location for example, I've learned that seeing is a limiting factor.  Also, my equipment needs upgrading here and there.  So, OF COURSE, I am looking forward to buying new equipment!

 

Clear Skies!

 

Jim Goodenough
AIC Webmaster




                                               



Old Friends: Heaven and Earth - October 2, 2017

It was fantastic to catch up with old friends during AIC 2017 this past weekend! After completing a few times around the Sun this conference offers some rare opportunities to connect with colleagues and company representatives from all over the world. New faces of imagers and vendors were also great to see and hint at the continued excitment for this hobby of astrophotography.

 

Just as revisting old friends is enjoyable here on Earth, each year offers the opportunity to revisit the constellations and star waypoints that mark the observing seasons in astrophotography. Objects in the sky that are available for a good fraction of the night, or are at their best, have cyclic seasons to observe them in. With respect to deep sky objects these windows of opportunity can be taken advantage of with a little planning. It is useful to recognize certain patterns in the sky. For example both Right Ascension and the catalog numbers of NGC objects increase in value towards the East. Knowing the Local Sidereal Time at sunset and/or when an object rises can quickly tell you if it is a good time to try to capture images of it. (Indeed, during the Fall near the equinox LST and local civil time are nearly equal.)

 

And perhaps this is precisely what you are thinking right now! having just attended AIC your head may be filled with many new and creative ideas concerning astrophotography and image processing. So setting up your system to capture some deep space wonder is high on the list and at this time of year there are some wonderful things to capture. 

During the fall the south galactic pole is rising at sunset. This means that for most of the night  from overhead to the south (from Northern Latitudes) far away galaxies reign supreme. At northern declinations, however, the plane of the galaxy glistens with star clusters and nebulae. So let us start there, closer to home and work our way out. The Bubble Nebula is probably one showiest and unique objects of its kind during this season. It rewards both wide field imagery with nearby star cluster M52 as well as the detail that can be garnered from long focal length systems. Short exposures and deep ones both again reward the imager- and even narrowband imagery is good for this object as well. 

 

Nearing the end of the season another nebula, perhaps slightly less captured- but no less rewarding- is NGC 1579. This beautiful multicolored menagerie of gas and dust might also be a good one to consider. 

In terms of galaxies the Andromeda Galaxy is of course visible nearly all night long. However when diving south this is also the season to look directly below our home galaxy and find NGC 253 (and faint globular cluster NGC 288). Like the nebulae above, this galaxy is superlative for all focal lengths and it is a great object to test our your new found AIC skills on. 

  Good luck, clear skies and great to see you this past weekend!

 

-Adam Block (new blog dude)




                                               



Mark your calendars for AIC 2019! - October 2, 2017

AIC 2019 will take place November 15-17, 2019 at the San Jose Convention Center.

 

Registration will open Spring 2019.




                                               



AIC Digital Library Update - October 2, 2017

Thank you for attending AIC 2017!  Now that the conference is over, we will begin adding presentations and videos from the event to the AIC Digital Library.  If you attended AIC 2017, you will receive a free AIC Digital Library Card that will enable you to review all of the presentations and workshop videos we recorded during the meeting.  You will also have access to every presentation since the first AIC, in 2004!  You will also be able to review the workshop videos from AIC 2015!

 

This digital library card will be effective until shortly after AIC 2019, which takes place November 15-17 at the San Jose Convention Center.  The new AIC Digital Library Cards will be sent, via email, on or around the middle of October 2017.

 

If you currently have access to the AIC Digital Library but did not attend AIC 2017, your Digital Library Card will be ended when we release the 2017 Library Cards.

 

We will be providing a way for people who did not or could attend AIC 2017 to purchase a Digital Library Card shortly.  Look for more information in the AIC Scintillion Newsletter, on the AIC Website and on the AIC Blog.




                                               



Room Rates - September 12, 2017

 
New AIC 2017 Hotel Discounts Available 
Attend AIC 2017 and save over 50% at the San Jose Hilton- only $189.00 per night!



Enjoy a greater than 50% hotel discount when you attend AIC 2017 and stay at the San Jose Hilton- conveniently connected to the McEnery Convention Center where the meeting is taking place. 

Rooms at this hotel normally cost over $350 per night. But, AIC has negotiated another exclusive block of rooms and is passing the savings onto 2017 meeting attendees. 

But hurry! This deal ends on September 21 (or when the blocked rooms are sold out- whichever comes first). 

Register for AIC 2017 

Book your hotel now!




                                               



Accelerate your imaging! Register for AIC 2017 Now! - May 10, 2017

Although the name suggests the annual AIC meeting is only meant for astrophotography experts, don't let the conference name mislead you. Each year the AIC agenda includes workshops targeted for novices, too.

Whether you're only curious, have started to purchase equipment and wonder how to properly use it or have taken your first images and are perplexed about how to process your data, the AIC is the best place to get the information you need quickly.

AIC has an ocean of information for folks who have many year's of expertise but it's not just for experts!

Astrophotography is one of the most complicated endeavors you will ever attempt. The number of moving parts is almost overwhelming- the mount, the electronics, the weather, the challenges of image processing and (to some extent) luck, all conspire to make your best intentions, hours of work and a small fortune in equipment wind up in the corner collecting dust.

 

On top of that, astrophotography is a self-taught exercise that does not garner a great deal of support from friends or family members. Sometimes family, neighbors or friends may ask, "Why do you invest so much time and treasure?"  Of course, this is just a kind way of saying, "Are you nuts?"  

That's why AIC was founded back in 2004. 

 

Each Advanced Imaging Conference is attended by enthusiasts who share your zeal and more than a few of your experiences. You'll quickly discover your excitement and frustrations have been felt by other meeting attendees. But, more importantly, you will receive an important ingredient needed to be a successful astrophotographer called encouragement. You will also be able to learn more in one long weekend than you will figure-out in over a year! AIC will help make the puzzle pieces fit together.

As a result, your imaging skills will become accelerated! Your images will start to take on a new level of sophistication.

So, if you are just starting out, I strongly recommend you come to this year's AIC! Think of AIC as the Accelerated Imaging Conference.

To help you accelerate your imaging skills, AIC 2017's agenda has been organized into sets of workshops, called tracks, that will help you select the most appropriate lectures to match your current skill level. For example, the Foundations of Astrophotography track will provide a wealth of information for enthusiasts who have been involved with the hobby for less than a year. By choosing this recommended set of classes, new astrophotographers will learn all the image production basics: from exposing to processing images using both dedicated astronomical cameras to inexpensive DSLR gear. Topics will include deep space, planetary and TWAN style pictures, too.

 

So, regardless of your imaging experience, if you want to improve the quality of your pictures, don't hesitate.  

 

Click here and register for AIC 2017 now!




                                               



2017 Golden State Star Party - March 2, 2017

Registration for the 2017 Golden State Star Party is open.

 

Visit the GSSP website here.

 

For those of you who might not have their own observatory or access to dark skies, this event is a great opportunity.  GSSP runs from Wednesday June 21 to Sunday June 25 2017.

 

If you are interested in going to GSSP, let's consider camping as a group.  Leave a comment to this message if you are interested and I will get in touch.

 

Jim Goodenough, AIC Board Member




                                               



Plan to Attend AIC 2017 - January 31, 2017

Mark your calendars, set aside Friday, September 29 through Sunday, October 1, 2017 and plan to attend the next Advanced Imaging Conference! Next year's meeting will convene at the San Jose Convention Center in downtown San Jose, California.

 

 

Friday morning and afternoon will be dedicated to workshops brimming with expert instructional advice covering image processing, data acquisition and the use of popular processing software applications. Then, the Friday night general session will feature presentations by the community's best and brightest stars!

 

Saturday and Sunday will also be packed with workshops from the hobby's best practitioners and, throughout the long weekend, AIC 2017 will showcase the latest technology from our community's leading vendors, manufacturers and service providers.

 

Saturday night will also include a special cocktail party, included in your registration fee, for the attendees.

 

Remember, AIC isn't just for experts or deep space imaging enthusiasts. AIC 2017 will cover the entire gamut of astrophotography: deep space, planetary, solar, cometary and both photo and video TWAN-style imaging.

 

But, don't come alone! Bring your spouse, companion or your entire family and, for a small additional per person fee, they can join our all day Saturday tour while you're at the meeting.

 

Registration will open in in just a few weeks.


     Comment(s) on Plan to Attend AIC 2017   

Username / Nickname: Jim Goodenough

I am looking forward to AIC 2017.  I have only been to one previous conference.  Just like my experience with astrophotography, I hope to learn more at a second event.  It seems like this passion requires patience and repetition.




                                               



Do you display your Astrophotography? - January 14, 2017

Double ClusterI am curious if after all the imaging, stacking, and processing if you display your images.  I am thinking either online or framed in your home or office.

 

For me, I do both.  I have several sites including social media where I post my photos, and I have a wall in my bedroom and also in my living room where I have framed the work.

 

I've purchased large format images either from the camera store or Costco (polished aluminum surface) that are reserved for my best of the best.

 

How about you?

 

Jim Goodenough, AIC Board Member




                                               



- December 12, 2016

Whilst this won't be as poignant as our AIC President Esq. Jay GaBany's holiday greeting is, I'd like to send out my personal wishes to my hundreds of friends in astrophotography, for a merry happy holiday season, and a safe, healthy, positive, and productive new year! We on the board of the AIC, are gearing up to make the 2017 meeting a highly substantive and enjoyable one for you. Keep in touch, clear skies, and here's sending lots of ancient photons your way!

Best, Warren Keller- AIC board member  

 

NGC 1365- SSRO


     Comment(s) on    

Username / Nickname: Lis
Wonderful! Thank you all for starting this blog with such great description! Looking forward to read more of your words! Happy Holidays, Lis



                                               



Being the Ghost of Christmas - December 12, 2016

Since Gutenberg's invention, millions of books have been published. Most are luxuries that add to a library already filled with good reading material but only a handful can be regarded as essential, compelling, necessary or must-reads. There are scores of favorites which enlarge our world view, deepen our understanding of the human heart, entertain through clever plots or intrigue with thoughtful prose. But there are scant few that universally embody the truth and when considering the truth, cause us to immediately recall the story. King Midas, the Grasshopper and the Ant represent two while others, like the Prodigal Son and Cain and Able, occupy the pages of scripture or, Prometheus, for example, lives in the lore of myth.

 

Charles Dickens' A Christmas Carol is one of these stories, too.

 

Self published by the author on December 18, 1843, within six days it has sold over 6,000 copies (which were subsequently pirated so that its initial distribution extended far beyond this number). It's a wildly imaginative narrative that celebrates Christmas in a most un-Christmas-like manner by summoning three ghosts who advocate for universal charity. Within its pages we watch as the main protagonist, a man of wealth who does not know how to enjoy the benefits of his accumulated treasure, learns to shed his avarice, share his good fortune and to have fun while doing it.

 

More than just a morality lesson, A Christmas Carol celebrates the joys of merriment, of bringing happiness to others and making otherwise common moments memorable. Scrooge's final triumph unfolds when he stares into his own grave and, instead of despairing, vows to live the remainder of his life to the fullest. By watching his transformation, we recognize our heart is likewise cold and thus, the three spirits of this timeless tale help emancipate us, too.

 

I have found that compassion, generosity and selfless giving, entreated so effectively by Dickens' short novella, thrives within the ever growing global community of astrophotographers, not just during the year-end Holiday Season, but all year-round! They are an all-volunteer group of explorers who pluck stars from the heavens with cameras and telescopes, coax the truth out of shadows and offer encouragement to others without expectation of reciprocation. This is the heart of A Christmas Carol's message and this great gathering knows how to keep the spirit of Christmas well, if any group or assembly ever possessed the knowledge!

 

To this throng I and the AIC board of directors wish Good Cheer and hope that you have a Dickens' of a Christmas both this Holiday Season and throughout the year!

 

Jay

 




                                               



Welcome - November 29, 2016

Welcome to the AIC BLOG. A BLOG is a "web log" - a place to exchange ideas, make announcements, share photographs, and offer support.

 

At this time, only "moderators" may initiate new threads. However, all users may place comments. Comments are moderated - reviewed - for appropriateness before being made visible to all users.

 

We hope you enjoy the AIC BLOG.