1.3  :  Latest news

2009-05-01: New release of Millennium website and databases

We have moved the Millennium databases to a new, more secure database server. At the same time we have slightly updated the web site. We here list the main changes to the system:
  • Millennium-II database
    • As announced here the FOF groups, subhalo-s and subhalo merger trees from the Millennium-II simulation are now available in the MillenniumII database.
  • Change to the comma-separated values format of streaming queries
    • We have made a change to the CSV format that is returned by the "Query (stream)" button on the web page, and which also it the data format that will be returned when using wget. In the old version of the web site the end of the file was either an error message in case a timeout happened, or simply the last row of data. The problem with this is that in case the timeout is not captured by the web server, for example because a connection between the client and the web server times out or breaks, there is no guarantee that the result is complete.
    If a result is completely returned without problems there will be an extra row at the end of the result that reads 
     #OK
    If this line is not there, and also no block of text starting with 
    #ERROR
    this indicates that users can not be assured that the result is complete.
    Note that this may cause some problems for client code that was built to deal with the old result type. In particular the TOPCAT visualisation tool may have to be upgraded. The TOPCAT programmer has produced a version that handles this correctly, though then it will always give a warning with the old web sites.
  • New MyDB-s have been created for all registered users.
    • They have been notified of ways to retrieve the data from the old web sites.
  • FAQ
    • Pages with frequently asked question have been added. Please feel free to ask us any question that is not yet asked or adequately anseewered there!

2009-03-18: Preparations for Millennium-II Simulation data

A new and complementary simulation to the Millennium Simulation, the Millennium-II Simulation, has recently been completed. The data will be added to this site in the next few weeks; much of the documentation for the Millennium-II has already been added to this site (see the simulation page on this site or the Millennium-II homepage for details on the Millennium-II Simulation). Registered database users will receive an email once the Millennium-II data are available at this site.

2008-04-029: Fix to Delucia2006_sdss2mass table

While investigating the MPAGalxies..DeLucia2006a_SDSS2MASS table we discovered that the H_2MASS and J_2MASS columns had been swapped. I.e. the values for H were stored in column J_2MASS and vice versa. The same was true for the DeLucia2006a_sdss2mass table in the millimil database. The 2MASS magnitudes in the Blaizot2006... mock catalogs in the MPAMocks database are correct. The mismatch has now been fixed on our side, i.e. J_2MASS copntains J and H_2MASS contains H.

2007-07-05b: Fixes and updates to the documentation

  • On page, the unit of np is Msun/h, not Msun.
  • The page on spatial indexing has been extended with a more complete description of how to use the spatial "zone" indexes, ix/iy/iz in the various tables.

2007-07-05a: updates to the database

Two new tables were recently added to the MField database available to registered users through the MyMillennium website. These are FOF and FOFSubHalo. The former contains the friends-of-friends groups that were the first post-processing products of the Millennium simulation. The second stores information about all the subhalos derived form the FOF clusters using the SUBFIND algorithm. From these subhalos are derived the subhalo merger trees that are stored in the MPAHalotress..MHalo table. The subhaloID in the latter table points to the subhaloId column in MField..FOFSubhalo and allows one to join from the MPAHalotress..MHalo to the FOF table through the fofId in the FOFSubhalo table.

2007-02-05b: Tutorial on Millennium database

Upon request a tutorial presentation has been put on this site. It can be downloaded as a Microsoft power-point from this link.

2007-02-05a: Mock all-sky SDSS/2MASS catalogues corrected

The Blaizot 2006, all-sky SDSS & 2MASS catalogues in the MPAMocks database have been updated and corrected for a mistake in the parameter file used to create them. The cosmological parameters differed slightly from those used in the Millennium simulation itself ( namely Ωλ/Ωm/h = 0.7/0.3/0.7 instead of 0.75/0.25/0.73). This latter mistake leads to a significant change in the mocks (mostly in terms of counts and redshift distribution). Please discard results obtained with the previous versions.

Note also that the unique "ObjID" of galaxies in the new mocks are now assigned in a random way and can be used to select random sub- samples efficiently (e.g. as with the "random" field from the table DeLucia2006a).

2007-01-23b: TOPCAT plug-in available

The webpage on TOPCAT now really gives a link to the plug-in that allows one to use this tool to query the Millennium/GAVO databases.

2007-01-23a: MPAGalaxies and Durham back online

After a problem with the system, the MPAGalaxies and Durham databases were unavailable. They have been rebuilt from scratch and are available again. The velocities in the MPAGalxies..DeLucia2006a table have also again been corrected for the problem identified in 2007-1-12.

2007-1-13b: New mock catalogues in MPAMocks.

We have added new mock catalogues in the MPAmocks database. This dataset contains 6 all-sky mock catalogues (tables Blaizot_AllSky_RT_x, with x = 1-5 and Blaizot_AllSky_PT_1). They are all limited at an apparent AB magnitude of 18 in the r filter from SDSS, in an attempt to reproduce (with some margin) the SDSS spectroscopic selection. The catalogues include apparent magnitudes in the 8 filters from both SDSS and 2MASS (namely u,g,r,i,z,J,H, and K). For a further description of this data set and some example queries see the documentation.

Note, these catalogues have been corrected for the peculiar velocity errors noted in news item 2007-1-12. This is true both for the line-of-sight velocity and apparend redshift of the observed galaxy, and for the velocities of the underlying galaxy. However, this correction was performed after the catalogues were created. This implies that the K-corrections used in determining the apparent luminosities were performed with the old, wrong values for the line-of-sight velocities. This effect is estimated to be very small, but these catalogues will be replaced with the rigorously correct luminosities as soon as possible.

2007-1-13a: Problems with peculiar velocities for type 2 galaxies corrected

We have corrected the problems decribed in item 2007-1-12 with the peculiar velocities of the type 2 galaxies in millimil..DeLucia2006a and MPAGalaxies..DeLucia2006a. We have also corrected the line of apparent redshift in the Kitzbichler pencil beams catalogues in MPAMocks. To this end we needed to add two columns to the table. More importantly, we did not correct the apparent luminosities. Formally thois would have to be done as well to take into account the slightly different K-correction. This effect is likely very small and can be ignored.

2007-1-12: Problems with peculiar velocities for type 2 galaxies

An error has been found regarding peculiar velocities for type 2 galaxies in the MPAGalaxies.DeLucia2006a. table, and the corresponding table in the millimil database. For these tables, the peculiar velocities (velX, velY and velZ) for galaxies with type=2 should be multiplied by a factor 1/sqrt(1+redshift) to get the correct values. This problem also affects the Kitzbichler catalogues in MPAMocks, though in a less direct manner (apparent redshifts and (very) slightly different k-corrections).

We will update the affected databases, but will need to bring them offline. We will add a news item when this has been fixed, until then it will be simple to correct for this in the DeLucia2006a tables in the indicated manner.

We appologise for this error.

2006-10-31: New: mock catalogues in database.

We have created a new database which will contain mock observational galaxy catalogues created by "virtually observing" the semi-analytical galaxy catalogues. This database is accessible to users with an account to the MyMillennium website. The first dataset contains 6 pencil beams based on MPAGalaxies.DeLucia2006a. They are the results of work published in Kitzbichler & White (2006), astro-ph/0609636. For a further description of this data set and some example queries see the documentation. Future mock catalogues will be published in this same database.

2006-10-20: Fixes in the database and web site.

Two errors were fixed in the database and web site.
First, the I and R-band magnitudes in the MPAGalaxies..DeLucia2006a table (available only on the MyMillennium website) were interchanged. The columns containing the I-band data, were named with R (mag_r, mag_rDust and mag_rBulge), and vice versa. This was fixed. This problem did not occur in the millimil..DeLucia2006a table.
Second, the documentation for the DeLucia2006a_SDSS2MASS tables in the millimil and MPAGlaxies databases mistakenly said that they contained Vega magnitudes. They are actually AB magnitudes. The documentation has been fixed

2006-09-26: SDSS and 2MASS magnitudes for MPAGalaxies.

A new table has been added to the MPAGalaxies database. This table contains observer frame magnitudes for the SDSS and 2MASS bands. It must be viewed as an addendum to the main table, DeLucia2006a. It can be linked to that table through the galaxyId column. For the schema of this table see this link. A version of this same table for the milli-Millennium simulaiton has been added to the corresponding database.