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"In astronomy, blazar, also known as BL Lac Objects or BL Lacertaes, are bright, starlike objects that can vary rapidly in their luminosity." ???

There is a verb missing, probably it's "change"=

BL Lac[edit]

Wait, isn't BL-Lacertae a subtype of Blazar... so the two terms are not equivalent, right? 01:15, 3 Sep 2004 (UTC) vary is the verb — Preceding unsigned comment added by 2602:306:BC44:B160:88DC:F2F4:4834:AFE1 (talk) 17:24, 26 April 2013 (UTC)

BL Lac vs Blazar[edit]

BL Lac and Blazar are not the same things. BL Lac objects are specific types of active galaxies, while Blazars are a grabbag of several different kinds of active galaxies, including BL Lac objects, and some subtypes of quasars, amongst others.

This article needs to be separated into Blazar and BL Lac, and cleaned up to separate the content properly. 03:37, 9 Sep 2004 (UTC)

made some major changes[edit]

I added a great deal of new information to this article, and will be adding more (along with some images) soon. Hopefully by the end of today.

The new changes emphasize that blazars are composed of two groups OVV quasars and BL Lacertae objects, the relativistic model (and therefore the unified model connected blazars with radio galaxies) is by far the best overall model. Also more specific details on the structure of a Blazar (basically the generic structure of an AGN).

I am working on adding a more comprehensive history connected the first qusars with blazars (3C 273 is a blazar, BL Lac identified in the 70s), and will mention more details about jet emission (synchrotron, inverse-Compton, and also the "blue bump" and emission lines in quasars). Also, not least, will tack on relevant references.

I also added a couple of short references like "host galaxy," and will treat the "relativistic jet" entry as another big one.

I used to do research in this topic (during the 90s), but that seems like another lifetime ago so it is quite possible I have screwed up by omission or stupidity. By all means feel free to check this all out.

Mrbrak (

Added more stuff - on relativistic beaming[edit]

I added a section on relativistic beaming, I'll stick some of the math (for a simple optically thin, synchrotron blob model of a jet) in a different article.

Time Dilation contributed a factor of D+1. This effect speeds up the apparent release of energy. If the jet emits a burst of energy every minute in its own rest frame this may be observed on Earth as being a much faster release, perhaps one burst every ten seconds. ??????????????????????????????????? Is this right? If two burst are separated by one minute in the local rest frame of the jet, the time separation would be larger than one minute to an observer on Earth, due to the time dilation. —Preceding unsigned comment added by (talk) 13:06, 19 October 2009 (UTC)

What IS the speed of a typical electron or proton in the jet? Is the typical speed relative to the bulk speed of the jet; higher?, lower?, variable?, constant? ... in other words ... it would be interesting to learn more regarding the relationship you are describing between the bulk speed of the jet and the speed of its constituents. This relationship is currently unclear. Thanks for your work on this article, it's very well written.

Copyright Violation[edit]

Please delete these images. I do not have permission of all of the authors of the original scientific article they were published in to publish them here.

Mr Brak 20:40, 17 April 2006 (UTC)


I'd like to see some sources listed for this article. Not only because it's good for the wiki, but I also have to write a bit about blazars for a course project and I don't want to quote the wiki without having something to back me up =) --19:18, 9 May 2006 (UTC)

blazar = gamma ray quasars?[edit]

According to this [1] (NASA), blazars are gamma ray emitting quasars... (talk) 07:51, 15 July 2008 (UTC)

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Relativistic Beaming - matter or energy?[edit]

This article contains the phrase "Relativistic beaming of electromagnetic radiation from the jet..". But according to the Relativistic beaming article, the term relativistic beaming refers to emitted matter, not energy. (talk) 13:38, 16 July 2018 (UTC)

Update in order[edit]

On January 22, 2020 the article still states “As of 2003, a few hundred BL Lac objects are known.”

Can anyone find an updated number? — Preceding unsigned comment added by (talkcontribs) 23:06, 21 January 2020 (UTC)