Home Page on L'Arciere Celeste

Enhance HII regions in Spiral galaxies

Sun, 12 Apr 2015 19:59:11 +0000

Galaxies are among the most fascinating objects to be photographed, their light emission comes mainly from the stars so it has a continuum spectrum.

For this reason, the primary capture method with CCD cameras is through RGB broadbandfilters ot get true-color images.

Some spiral galaxies, however, are very rich in HII regions, areas in which star formation is particularly active, and emit mainly hydrogen spectrum whose main emission line in the visible, called Hα (H alpha), is in red at 656.28 nm.

About

Sat, 20 Jun 2026 00:00:00 +0000

Edoardo Luca Radice

My name is Edoardo Luca Radice. I was born in Saronno on 20 July 1969 — fifteen minutes before Neil Armstrong uttered the famous words “Houston, Tranquility Base here. The Eagle has landed”.

I earned my degree in General Physics at the University of Milan, with a thesis on X-ray emission in compact clusters of galaxies. I describe myself as a non-practising astrophysicist: in Italy, pursuing an astrophysics career is difficult, especially in the early years, and it demands sacrifices I was not willing to make. So I chose to make physics and astronomy a serious hobby and to devote myself to another profession. Astronomy, however, has never been one interest among many to me: I have no memory of becoming fascinated with the sky, because the sky has always been with me.

Contact

Wed, 17 Jun 2026 00:00:00 +0000

You can find me on:

Testing the REEGO Pro 2 collimator with MO.R.

Sat, 17 Jan 2026 11:21:30 +0000

The REEGO Pro 2 is a high-level universal collimation tool, designed for those who want to go beyond laser and Cheshire and achieve a truly accurate alignment of the entire optical system. It is particularly suited to Newtonians, but it also proves useful on other optical configurations (which, however, I have not had the chance to try), and in particular for checking the centering of refractor optics.

Tecnosky CARBON Series Newton 200/800 astrograph

Mon, 24 Mar 2025 21:49:13 +0000

During my talk at Luca Fornaciari’s Astro Pub in January 2025 I had stated that I had never tried Newtonian telescopes for astrophotography.
A few days later, Giuliano Monti of Tecnosky contacted me to suggest I test their Newton 200/800 CARBON Series: a classic telescope with a 200 mm parabolic primary mirror and an 800 mm focal length, which provides an F/4 focal ratio.

Flat Killer 20250 the Review

Sun, 30 Jun 2024 14:34:00 +0000

A few months ago (April 2024) I was contacted by Alessandro Roso and TS Italia Astronomy to try out a new flatbox.

The matter seemed interesting to me right away, since the acquisition of flat fields for an accurate calibration of images has always been one of the most debated topics in the world of astrophotography.

Correcting bias drift through overscan calibration

Fri, 12 Aug 2022 15:01:50 +0000

Image calibration is a crucial step during the pre-processing of astronomical images; this short article takes a closer look at the calibration of cameras that suffer from the phenomenon known as bias drift, thanks to calibration using the overscan area.

Beloved Flat Fields

Fri, 12 Aug 2022 07:13:22 +0000

Calibrating astronomical images is one of the key steps to achieving a quality result, and one of the most important steps in this phase is the application of the flat field.

During my PixInsight courses all over Italy, one question, unrelated to the use of the software but of fundamental importance for image calibration, is: how many ADU should I make my FLATs?

The M@H (Messier At Home) Project, in collaboration with MSI Italy.

Mon, 29 Nov 2021 22:36:19 +0000

As a city astrophotographer, in a city of the Po Valley — a region that suffers from one of the worst levels of light pollution in Europe — my first goal has always been to find clear, dark skies from which to shoot my images.

New PixInsight Script: LinearStarNet

Sat, 02 Jan 2021 20:23:13 +0000

Warning! This article is now out of date and no longer applicable. Neural network-based tools can now handle both linear and nonlinear images perfectly, so LinearStarnet is no longer distributed.

StarNet++ is a very interesting project by Mikita Misiura.

It’s a neural network based software to remove stars from astronomical images, and it does surprisingly well.

Playing with the Great Conjunction of Jupiter and Saturn

Wed, 23 Dec 2020 23:03:51 +0000

Anno Domini 2020, December: media all over the world take an interest in a rare astronomical event — the conjunction between Jupiter and Saturn.

Conjunctions between these two planets recur at intervals of about 20 years, but this one had a special feature: at the moment of closest approach the two planets would be just over 6 arcminutes apart.

Color ZWO ASI 6200 test

Fri, 20 Nov 2020 01:00:53 +0000

leggi l’articolo in italiano

Many of the astrophotographers of my generation, after passing through analog photography, approached digital astrophotography for the first time thanks to CMOS sensors.

Only a few, in fact, could afford the first cooled CCD sensors for astronomy: they were expensive, small and difficult to use, reserved for professionals or advanced amateurs.

Verifying the linearity of image sensors: going beyond linear regression.

Tue, 13 Oct 2020 21:14:11 +0000

One of the most debated and least understood issues among non-specialists is the so-called linearity of electronic image sensors.

CCD and CMOS imaging sensors should possess one fundamental characteristic if they are to be used for scientific purposes or even just for advanced astronomical imaging: the sensor’s response to light must be linear.

Creating near true color images for nebulae from narrow band data using PixInsight

Tue, 08 Oct 2019 19:17:28 +0000

This is the video of my Workshop held at CEDIC 2019 in Linz.

It shows a way to compose narrow band data of emission nebulae into a near true color image.

The presentation can be downloaded HERE

PixInsight Script: Correct magenta stars

Wed, 02 Oct 2019 22:38:45 +0000

Leggilo in italiano

Thanks to the collaboration with Roberto Sartori here our first PixInsigth script.

to be honest there is very little of me in it, only the “technical direction”, the programming part was done entirely by Roberto.

The script is used to quickly and effectively correct the problem of magenta halos that appear around the stars when the narrow band images are combined to form the so-called Hubble Palette.

Optolong L-eNhance filter test

Sun, 22 Sep 2019 13:51:06 +0000

Light pollution: the Nemesis of every urban and suburban amateur astronomer.

Whether you are a visual observer or a photographer, one of the greatest obstacles to your passion is undoubtedly the rampant phenomenon of light pollution.

PixInUmbria: Sabato 2 e Domenica 3 Novembre 2019

Wed, 14 Aug 2019 08:45:03 +0000

La fotografia astronomica moderna, basata sui sensori digitali, non termina alla fine della nottata di acquisizione delle immagini, una seconda e fondamentale fase attende il fotografo: l’elaborazione delle immagini.

Le informazioni sul soggetto astronomico ripreso sono nascoste sotto strati di disturbi: Rumore, Inquinamento luminoso, Vignettatura ecc.

Una volta risolti questi problemi l’immagine grezza lineare ha ben poco da dire: è necessario elaborarla in modo da evidenziare i più tenui dettagli raccolti dal sensore.

The colors seen by visual astronomers? Mere illusion

Tue, 04 Dec 2018 21:56:55 +0000

Here is the video of the Conference held together with my friend Lorenzo Comolli (http://www.astrosurf.com/comolli/) about the possibility of seeing the colors of astronomical objects during visual observation at the telescope.

The title, deliberately provocative, says that the perception of colors is, in large part, due to an “optical illusion” caused by the physiology of the eye and the mechanism of vision.

Processing comet images

Sun, 16 Sep 2018 19:03:43 +0000

In this video tutorial it will be explained how to process comet images so as to obtain the image of the comet stationary among the stars.

The starting data are a series of shots taken by my friend Emmanuele Sordini (http://www.bloomingstars.com/?lang=it) using a Baader-modified Canon EOS 6D mounted on a Pentax 75 SDHF.

When BatchPreprocessing fails.

Sat, 17 Feb 2018 13:32:59 +0000

This tutorial, created by Edoardo Luca Radice and Vittorio Liberti of the Astrofili Veneti (http://www.astrofiliveneti.it/), aims to analyze and solve one of the possible problems that could be encountered when using PixInsight’s BatchPreprocessing with the Default values.
Using BatchPreprocessing with the default values, the final result was the following (as an example, only the image obtained with the SII filter is used).

Video guide: ScreenTransferFunction and HistogramTransformation

Sat, 17 Feb 2018 13:25:54 +0000

An extremely simple introductory video on the use of PixInsight’s basic tools:
ScreenTransferFunction
HistogramTransformation
CurvesTransformation

Designed for black-and-white images

Dual-scope photography

Mon, 29 Jan 2018 14:48:14 +0000

In the February 2018 issue of the magazine Nuovo Orione, an article written by Luigi Fontana appeared about the acquisition and processing of images acquired with two different setups.

In the article, in a sidebar, I explained how to apply the composition technique with PixInsight.

Video guide: processing NGC 891

Tue, 30 May 2017 11:44:40 +0000

During the “brainstorming” session of the PixInsight Workshop at the Torre del Sole on May 27 and 28, 2017, I was asked for advice on how to process an image of NGC 891

The image is an LRGB capture taken from the city sky of Manerbio by my friend Alberto Crescenti.

LRGB composition in the linear stage with PixInsight

Tue, 14 Mar 2017 22:38:08 +0000

INTRODUCTION

In recent years, astronomical photography with “aesthetic” purposes has spread widely among enthusiasts thanks to the advent of increasingly sensitive electronic sensors at affordable prices.

The Astro Imaging Channel: Challenge nr 1

Wed, 17 Jun 2015 20:56:08 +0000

On Monday June 22nd 2015 The Astroimaging Channel proposed an image processing challenge (read here) based on a set of RGB images of the Markarian chain.

This was the challenge:

1. Gradient Removal while preserving star color.
A few months back, I wanted to try imaging my blue channel high up in the sky. It didn’t work out as planned and I have a terrible gradient through the image. I’ve been able to get rid of the gradient, but it leaves a bad color cast through my stars. The challenge is to remove the gradient and preserve the star color.

Narrowband color composition using J-P Metsavainio Tone Map technique in PixInsight 1.8

Fri, 17 Oct 2014 12:24:49 +0000

Leggilo in Italiano

Recently I began to take astronomical pictures in narrow band using my SBIG ST2000XM and a set of Baader Filters (Hα, Hb, OIII and SII).

One of the most famous color composition technique of narrowband data is the Hubble Palette that gives to nebulas a typical golden-turquoise color palette.
In this composition the SII emission is associated to Red, OII to Blue and H alpha to Green.
The drawback of this composition is that, since Hα widely dominates on OIII and SII emission, OIII and SII image histograms should be boosted relative to Hα, this bloats stars and creates weird magenta halos.

PixInsight processing example | Goddchen M8 processing contest

Wed, 20 Aug 2014 14:00:02 +0000

Leggilo in italiano

I recently participated in an astrophotography processing contest promoted by Martin Liersch website.

The contest was focused on a picture of M8 taken on a quite light polluted sky: this image is an example on how PixInsight could be great on dealing with such problematic pictures.

These the technical data of the image:

Creating seamless lunar mosaics in PixInsight

Thu, 03 Jul 2014 20:55:10 +0000

Leggilo in italiano

INTRODUCTION

As everyone knows PixInsight is a formidable tool for deep sky astrophotograpy processing: it gives to the imager a lot of tools that goes from preprocessing to the final touch on any astronomical picture.

Less knows that PixInsight is a powerful tool for planetary processing too.

Steve Cannistra Bicolor composition in PixInsight

Wed, 28 May 2014 20:03:54 +0000

Leggilo in italiano

INTRODUCTION

In recent years narrow band filters astrophotograpy has spread widely among amateurs for various reasons.

Personally I chose this technique because I can successfully take pictures from skies with a certain amount of light pollution.

The better targets for this kind of photography are emission nebulas like HII regions and planetary nebulas, objects in which the light emission occurs in narrow spectral bands.

Modeling comet Lovejoy 2013 R1

Tue, 10 Dec 2013 11:16:15 +0000

Leggi la versione in italiano

Recent observations of comet C/2013 R1 Lovejoy showed the presence of characteristic structures in the vicinity of the jet fake comet’s nucleus.
Such structures can be explained by the presence of collimated jets of gas and dust emitted from the surface of the comet nucleus.

This article attempts to interpret some observations in order to create a kinematic model of the comet’s nucleus.