How can I calculate the mass of my observed galaxy?

To calculate the mass of an observed galaxy, just put the observed magnitude information for your galaxy in the normalization tab of the web interface. Then, check the 'Stellar Masses' output column in the Output tab. The stellar masses output by EzGal will be the stellar mass of your observed galaxy as a function of redshift.

Exactly what masses are returned by EzGal?

Currently, all the model sets return stellar masses which include living stars + remnants. This has always been true for all the model sets except the CB07 and BC03 models, which were updated to match the others on 05/10/2012. The difference between including and not including remnants is most important at late ages (low redshifts). It can influence the stellar masses at the 10-20% level.

What BaSTI models do you distribute

The BaSTI models include an optional mass loss parameter, 'n'. All the models distributed on the EzGal website have 'n'=0.4. Also, we use the low resolution models, as the high resolution models are not normalized for use in calculating absolute fluxes.

What Maraston models do you distribute?

The models from Maraston 2005 are distributed with a blue and red horizontal branch. All the models distributed through EzGal make use of her RHB models.

What version of the FSPS models are you using?

Currently the FSPS models (Conroy et al. 2009) distributed with EzGal come from FSPS v2.3.

Can you add filter X to the web interface?

Yes. Once I have the transmission curves for a filter, it doesn't take much work for me to add the filters. My computer does more work - it takes about an hour or two for my computer to calculate and store the redshift evolution of a single filter, model, and formation redshift. EzGal itself is decently fast, as it only takes a second or two to calculate the redshift evolution for a model with one formation redshift through one filter. However, I have ~350 models on the web interface with 9 formation redshifts for each model, hence an hour or two.

So I'm happy to accommodate requests for new filters (just email me). If you can though, it would help if you can provide me with the filter transmission curves.

What happened to the short burst models that used to be on the web interface?

At the moment all CSP models distributed through the web interface were calculated with EzGal. This removes any systematics that might have been caused by different numerical methods with different model sets. It also allows me to distribute CSP models for model sets even if they aren't provided by the model sets themselves. However, at the moment I don't trust EzGal CSP calculations for star formation histories with discontinuities, i.e. a burst of star formation which goes from some finite value to zero instantly. Therefore, I've removed these models from the web interface. Also see this note.

ezgal.model() doesn't work. What gives?

With previous versions of EzGal I forgot to package EzGal in a folder - I just zipped up the python files. As such if you unzipped it in your python path, the 'import ezgal' command would import instead of the ezgal module (which declares things like ezgal.model() and ezgal.utils()). To fix this, download the latest version of EzGal, and make sure that the ezgal folder is in your pythonpath.

What's with the name? I mean, EzGal?

Yes, indeed. I didn't originally intend EzGal for distribution and so I originally just called the script ez_galaxy. As it's utility increased and we decided to distribute it more broadly, it was suggested to come up with a better (and shorter) name. I'm not very good with coming up with names, and I just shortened it to EzGal. The oblivious person that I am, the unfortunate connotations of this name never occurred to me. Almost 2 years later, and after EzGal was being widely used and could no longer be renamed, my wife finally pointed out my poor choice of name. I've since given up all my rights for naming any of our future kids and/or pets.