The Uniform Low Dispersion Archive (ULDA) is a software system which. in a single sitting, allows you to obtain copies on your computer of those IUE (International Ultraviolet Explorer) low dispersion spectra of interest to you.
The search programs and data base are maintained by the European Space Agency (ESA) at the ESA IUE Observatory Villafranca. Spain (VILSPA) and updates are sent from them to the national host sites. Regular updates to the user ID files are done by VILSPA. The NSSDC is currently running version ?.0 which contains approximately ? images.
The ULDA software is menu-driven from within the National Space Science Data Center (NSSDC) captive account (NODIS). The ULDA user does not need to have the IUE/ULDA Coordinator intercede in order to access the data or search routines. It is a reasonably self-contained series of programs and a data base.
NSSDC is the United States national host site for users within the U.S. and a temporary host to astronomers in other countries that do not have an established national site.
The overall concept is that research institutes within a country are served by a single national host which can be accessed using intercomputer links. This center holds the ULDA as a relational data base as well as the software to interrogate and select spectra from the data base. In order to ensure that everyone has access to the same data ,these national hosts are in turn served by a principal center.
Below are the two ULDA programs you will use:
The search program runs at your national center while UNSPL runs at your local
computing center. The following section comprises an overview of how to use
the ULDA and its components.
Retrieving spectra in a form suitable for your image processing system
comprises a two or three
stage process, the number of steps required depending on the nature of your
connection to your
national center. The steps required are described below.
When you log in to your national center's ULDA account from your institute
, you will enter the
Query/Select program through the NSSDC NODIS account. A user can initiate a
new search for
data or recover a previous file that may not have successfully been
transferred to the user's node
If a search is chosen. the program writes the data to several user files and
returns the user to the
SELECT menu. Here users may edit the files. view the files and/or save the
files they wish to
transfer to their host nodes.
The search menus start with a specific search target and regress to a wider
,more general search
window with each new menu display. A "?" in any of the search displays could
yield further examples and/or clarification of what is expected within that
panel. This is particularly useful when
you have reached the Object Class and Homogeneous Object ID menus.
This stage is required only if you are not connected to a national center by
DECnet. To begin this
stage, copy the spectra you have selected (held on a single file) to your
computer using either a filer
transfer system (e.g.. KERMIT) or computer mail. The Query/Select program
affords you the option of outputting the spectra in compressed ASCII encoded
form which is
essential if you intend
to use Email or a file transfer system which does not support the transfer
of K blocks of binary
data. If you have saved auxiliary data (e.g. what a search found) these
will be in ASCII format
and should be downlinked as well using Email or a file transfer system.
To generate individual spectral files having a format suitable for your image
processing system,
run program UNSPL on your computer. UNSPL (UNscrambler/SPLitter) will
downlink your data
for you from the national host if you are connected to it by a DECnet link
(these data comprise
your spectra and auJdliary information). The following two diagrams
illustrate what this stage involves if you are connected to the national host
by a DECnet-like link or not.
No DECnet link to National Center
With a DECnet link to National Center
If you ignore all but the absolutely essential actions required, you are left
with a three stage process.
EXAMPLE: Find spectra taken with the SWP camera for objects with class
57 or 58.
Reply SWP to the camera/lmage number/aperture prompt
and Reply 57,58 to the object class prompt.
Enter the SELECT command from the main menu and a description of the spectra
found by the
last search will be displayed a screen at a time. These descriptors
(ie.. camera image number,
aperture, homogeneous ID, coordinates, date of observation) take one line
each and are prefixed by
an Index (ranging from one to the number of spectra found) used to perform
the selection.
EXAMPLE: Suppose you want the 5th. 6th. and 20th. spectra
displayed:
When you have picked the spectra you want, type E and the ULDA will terminate.
From this you
can see that SELECT is not cumulative (which is also true for the other data
base commands; for
example the output from a search overwrites the previous search's results).
Your output from the ULDA is stored on work files whose names comprise your
ULDA ID (see section 3. [LOGIN])
and standard qualifiers. These files are listed bdow.
Note :
Logging in to the ULDA will normally involve entering your ULDA ID and a
number from a menu. However, certain additional functions are also
available to you at startup. For Instance:
On entry the ULDA will ask you to enter your ID. Such an ID should have a
two-letter country ID
followed by up to six nonspecial characters and must have been given to you
by the ULDA in a pre
vlous session. Examples of valid IDs are: UKJO Jo in the UK, WGINGE Inge in
West Germany.
Since IDs define your output file names under no circumstances, use someone
else's ID since you will erase his data files. If you
have forgotten your ID,
sec section "Dlsplaylng the IDs and Ihelr Owners' Names for a Country",
or if you do not have
one, see section "Getting an ULDA ID (Registration)".
To avoid delays the ULDA allows you to register yourself, a process you need
to do only once.
When the startup prompt is displayed on the screen, reply "R" and the possible
countries and their
two-letter abbreviations are displayed (the two character codes will be the
first two letters of your
ID). You are then prompted in turn for each of the following:
Should you forget your ID or have difficulty choosing one use this command
by replying "D" to the
startup question as indicated on the screen. The possible countries and
their two-letter abbreviations will be displayed.
GIVE A COUNTRY'S 2 CHARACTER ABBREVIATION OR X (OR EX) TO EXIT
If you enter the country's ID only, it will display all the registered users
of that country.
If you are unable to downlink all the spectra you chose, you may send the
ULDA into recovery
mode by giving your motive for using the ULDA as recovery" (in answer to the
second question). If
you ask for recovery, you will not go through the normal pathway but will be
sent directly to the
SELECT command where you will be able to choose spectra from those selected
during the previous run.
EXAMPLE: Suppose you only managed to downlink and unscramble
(using UNSPL) the first
two spectra you selected. In this case, reenter the ULDA, go into
recovery mode and reply as follows to the Select prompt : 3-100
Your id.SPE work file will now hold only those spectra you were unable to
download.
Please note that, when in recovery mode:
Before describing the SEARCH function, it is worth remembering that your goal
is the selection of
spectra which, as illustrated in the diagram below, the ULDA helps you do
in a two-step procedure. First, do a data base search for a set of spectra
which includes those you want and secondly select those spectra you want.
See the graph below.
The search itself is invoked from the main menu in two forms, differing only in
the amount of explanatory text which is displayed. Because of the easy nature
of the search and because the "short" format form gives free examples and
prompts, this is how you will start your searches except for the first couple
of times .
You may search on one or more of four types of criteria, each of which you
will be prompted for in
turn. A carriage return will skip the search menu currently being
displayed. The possible
search class are as follows:
Each search element comprises a maximum of three fields written as a
contiguous string. These fields are below:
If all three of the above are given (e.g.. SWP12345L), you will specify a
spectrum uniquely (the maximum number of spectra found will be one). However
, any combination of one to three of the fields
is also valid, provided the order of [Camera] [Image number] [Aperture] is
preserved within a query element.
Examples of some valid search requests follow:
EXAMPLE: Find all spectra with image numbers 12345 or 12551 or spectra
taken with the SWP and having image number 1673:
CAMERA IM.NO.AND. AP'S: 12345,12551,SWP1673 <CR>
Your understanding of the logic is in good shape if you see that "LWRL" is not
the same as "LWR L."
LWRL = Find all spectra taken with the LWR and the large aperture.
LWR L = Find all spectra taken with either the LWR or with a large aperture
(useless request)
Search requests are always composed of pairs of coordinates in the order RA
then Declination.
Both coordinates of such a pair must be given on the same input line and be
separated by one or
more blanks. If you wish to enter more than one pair, they should preferably
be on separate input
lines, though they may be on the same line, separated by one or more spaces
commas. or semicolons. Valid coordinates are one- two- three- four- or
six-digit integers which may be signed for
Declinations only. In addition, either coordinate may be entered as "ALL" or
"*" (in which case the
search will be made on the other coordinate only).
EXAMPLES: 5 hrs. 8 mins. (of RA) must be represented by 0508; however
5 hrs. of RA can be entered as either 5 or 05.
Each sky position you enter actually is a search window whose dimensions are
determined by the
accuracy with which you specify the coordinates. For example, if you give
hours of RA, only you
will get a larger range of RA (by default) than if you specify hours and
minutes, which in turn give
a larger default range than if you specify the RA down to seconds. The
"fuzziness factors" for the
various previsions of coordinates are given in the following table, which you
can display anytime with the RA./Dec. help (i.e,"?").
See the following diagrams for an illustration of how implicit ranges work
Search Windows for Two Different Requests for RA= 8 Hrs Dec.= 6
For request = 86 For request = 08006
Search window: Search window
MANQUE UNE FIGURE
Window generated by "8 ALL"
MANQUE UNE FIGURE
IUE object classes are integers in the range 0-99 whose meaning you can
display within a search
by using the object class search query's help (i.e. "?"). If you want to
search on more than one
class at a time, separate them by one or more commas, blanks or semicolons
, or enter them on separate lines.
EXAMPLE: Search for pulsars and supernova remnants.
OBJECT CLASSES: 62, 75 <CR>
The IDs comprise a catalogue (one to four letters) followed by the object's ID
within it. If the latter
has two parts which are not a pair of celestial coordinates
(e.g.. BD -17 4554),
these must be separated by one or more spaces. Otherwise, do not insert
blanks. Spaces between the catalogue and
the ID are optional except for catalogues which are prefixed by AOO
(Any Other Oblect) when a space is required after the catalogue.
EXAMPLES:
If you specify more than one ID to search on, it is preferable to put them on
separate input lines, though you can enter them on a single line separated
by commas or semicolons. Please note that
unlike all the other search queries a space is not a request separator.
The catalogues ordered by their priority are as follows:
AOO is composed of catalogues not listed above plus those objects which could
not be uniquely identified.
Note: Spaces are optional between the above catalogue IDs and their entry but
mandatory between an AOO's subcatalogue and Its entry.
DISPLAY is invoked from the main menu and shows what the last executed search
found, one screen
at a time, up to a host center dependent number of records (400 when
distrlbuted). See the following sample output (the search was for oblect
class 40).
The Usage/Dubious column contalns flags, "U" and "D" respectively, whose
presence indicates
that auxlllary lnformation is available and what type it is (see
section:
(Auxiliary Information: Dubious and Usage Data). Usage data wlll tell you
who has selected thls
spectrum prevlously
while "Dubious" comments usually indicate why the flux units of the spectrum
mnay be in doubt or
should be treated wlth care. e.g.. trailed spectrum. no exposure time avallable.
This function, which is executed from the main menu, saves the descriptors of
what the last
search found, onto your work file id.DES (where "Id" is your ULDA ID). The
format on the file is almost identical to DlSPLAY's wlth the
text prefixed by your
search request. Like DISPLAY only the first 400 finds are saved.
One possible applicatlon of the command is for those who would like to look at
the list of spectra at their lelsure.
Note: If you issue the command more than once, your work file will hold
the result of the last Save Descriptors only. However, remember the
descriptors of any spectra you
subsequently select will be appended automatically to your descriptor work file.
SELECT, which is started from the main menu enables you to pick those spectra
of interest from
those found by the last search. The spectra you choose will be stored in your
work file id.SPE
(where id is your ULDA ID), their descriptors in id.DES and their usage data
appended to id.AUX.
Before starting the selection you are asked if you want the spectra that you
will select to be encoded in compressed ASCII format (the default output
being 2K binary blocks).
DO YOU WANT ASCII ENCODING OF SPECTRA?
If you Intend to E-mail the data to your computer or will be using a
KERMIT of limited
power then ask for ASCII encoding (each spectrum, its header and epsilons
call be compressed
and converted into universally recognised ASCII characters and altogether will
take between 20
and 26 lines of text, each 72 characters long). Please note that ASCII
encoded spectra will be illegible to all programs except the UNSPL which
will convert spectra into the format you want.
SELECT displays the descriptors of the spectra found by the last search in a
format and a manner
identical to those used by DISPLAY. The only difference is the bottom prompt
lines which include
an example and read as follows:
GIVE REF.NOS.(E.G. 3 8) AND/OR RANGES(E.G.3-8) TO SELECT/END/NEXT OR
LAST PAGE
NEXT (CR) OR PREV.(-) PA<E/E/SELECT LIST
You select spectra by using the reference numbers in the first column of the
display. You may either select spectra individually or as ranges by
entering the reference
numbers or ranges separated
by commas spaces or semicolons or by putting them on separate input lines.
EXAMPLE: Choosing individual spectra: 3, 7, 9, 14
Should you specify a spectrum more than once, only one copy will be made.
Note:
Two forms of auxiliary information are available as described below. Both
are being output to
your id.AUX work file (where "id" is your ULDA ID), if they are displayed.
For dubious comments display and filing use the DUBIOUS command in the main
menu. All the dubious comments are displayed and filed (on your id.AUX work
file) for the first 400 spectra found by the last search. For usage data
display and filing use the SELECT command. When this terminates, if any
spectra have been selected that have usage data, you will be asked if you want
to see it. If you reply "yes ", it will be shown on your terminal and appended
to your id.AUX file.
Since the output from the ULDA will be in a compressed format, a program
(UNSPL) is supplied by
your national host site to unscramble your file of selected spectra and split
it up into separate files,
one per spectrum, with a format suitable for immediate processing. Every end
user institute will have its own version of UNSPL running on its computer
tailored suitably if necessary to its particular needs.
A useful additional feature of UNSPL for users connected to their national
center by DECnet is the optional automatic down link of their work
files:
To execute the UNSPL, type in "UNSPL". UNSPL will ask you a few simple
questions to determine what it has to do.
The user's compressed spectral work file is split into a number of ASCII
files containing one spectrum each. Such files have a table format: the
first column contains wavelengths, the second
contains absolute fluxes (ergs/sec/cm2/A), and the third contains
quality flags
in standard IUE format (epsilons). This format can be used as input to a
surprising number of image processing systems and it allows printouts of
spectral data.
The name of each output file is built with the camera, image number and
aperture keywords; the file extension is ASC (e.g.. the file concerning
image number 12460 obtained from camera SWP with large aperture, will
be assigned the name SWP12460L ASC).
Records may be read subsequently using the FORTRAN statement
: READ (n.*) WAVELEN,FLUX,IEPSIL
Another standard output format provided by UNSPL is FITS, with the "Image'
extension. Each output file contains one spectrum in the format described
in the following.
Block 1 of the FITS file contains the file header. The following FITS
keywords are filled, some with
fixed values, some with the contents of the user work file record header.
Block 3 of the FITS file contains the extension header. The following FITS
keywords are filled, some with fixed values, some with the contents of the
user work file record header
The name of each output file is built with the camera image number and
aperture keywords; the
file extension is .ULD (e.g. the file concerning image number 12460 obtained
from camera SWP
with large aperture will be assigned the name SWP12460L.ULD).
MIDAS is a data processing system commonly available in Europe. The
compressed user work file
is split into a number of files in MIDAS format: The data of each spectrum
constitute a one-
dimensional "bulk data frame" (BDF) file, while an additional file of type
"table" is provided to hold
the epsilons of each spectrum. A table is composed of three columns: The
first contains the
wavelengths of all the data flagged as of "bad quality" data, the second
contains the value of the
quality flag and the third contains the "bad quality' data themselves.
The name of each output file is built with the camera, image number and
aperture keywords; the
file extensions are .BDF for the bulk data frame file and .TBL for the table
file (e.g.. the files concerning image number 12460 obtained from camera SWP
with large aperture will be assigned the names SWP12460L.BDF and
SWP12460L.TBL respectively).
At UNSPL installation time, itis possible to provide a routine allowing
output of spectral files in a
locally-defined format. If such a format is available at your institute,
refer to your own system's
data processing documentation for additional information.
3 How to Use the ULDA (Overview)
4 Stage 1: Search and Select Spectra
5 Stage 2: Transfer Data to Your Computer
6 Stage 3: Generate Spectral Files on Your Computer
7 Overview of How to Run the Query/Select Program
8 GENERAL CONSIDERATIONS:
9 THE MINIMUM YOU HAVE TO DO:
10 LOGIN
11 SEARCH
You may search on one or more of the following:
You will always be prompted for the above four classes of input (carriage
return <CR> for those you
do not wish to use). If you reply to more than one of the above types of
search criteria, the search
will be for the intersection of the hits found for each set.
12 SELECT
Reply 5, 6, 20 OR 5-6,20
13 OUTPUT FROM THE ULDA:
14 How to Use the ULDA (for Reference)
15 FUNCTIONS AVAILABLE DURING LOGIN
16 Giving your ULDA ID
17 Getting an ULDA ID (Registration)
18 Displaying the IDs and Their Owners' Names for a Country
ID - Country ID - Country ID - Country AA - Austria AR - Argentina AU - Australia BE - Belgium BR - Brazil CA - Canada CH - China CI - Chile CK - Czechoslovakia CO - Colombia DK - Denmark EQ - Equador FI - Finland FR - France HL - Switzerland IN - India IR - Ireland IS - Israel IT - Italy JA - Japan LU - Luxembourg ME - Mexico NL - Netherlands NO - Norway PE - Peru PO - Poland PP - Portugal SP - Spain SU - Soviet Union SW - Sweden TW - Taiwan UK - United Kingdom US - United States VE - Venezuela WG - West Germany 19 Recovery Mode
20 SEARCH FUNCTION
FIGURE MISSING HERE
21 Overall Search Rules
Putting one search element per line is often the best option. If you make a
detectable typing error, the line is discarded. Furthermore, the separation
between requests stands out better.
22 Search on Camera and/or Image Number and/or Aperture
In all search requests you can specify a list of criteria separated by
commas, spaces, semicolons,
or (preferably) by entering each element on a separate line, in which case
the list elements will be joined by logical ORs.
23 Search on RA and Declinations
Search Window Sizes R.A. DECLINATION Accuracy Used Window Size Accuracy Used Window Size Hours Only +30 Mins. Degrees Only +4 Degs. Hours + Minutes +10 Mins. Degrees + Minutes +/-25 Mins. Hours +Mins +Secs +30 Secs. Degrees + Mins + Secs. +/-1 Min. 24 Search on IUE Object Classes
OBJECT CLASSES 0 - 29 0 Sun 10 WC 20 B0-B V-IV 1 Earth 11 WN 21 B3-B5 V-IV 2 Moon 12 Main Sequence O 22 B6-B9,5 V-IV 3 Planet 13 Supergiant O 23 B0-B III-I 4 Planetary satellite 14 Oe 24 B3-B5 III-I 5 Minor planet 15 Of 25 B6-B9,5 III-I 6 Comet 16 sd O 26 Be 7 InterplaneL medium 17 WD O 27 Bp 8 Giant red spot 18 28 sdB 9 19 UV-strong 29 WDB OBJECT CLASSES 30 - 59 30 A0-A3 V-IV 40 F0-F9 50 R,N,S TYPES 31 A4-A9 V-IV 41 F3-F9 51 Long Period Variable 32 A0-A3 III-I 42 Fp 52 Irregular Variable 33 A4-A9 III-I 43 Late-type degen.stars 53 Regular Variable 34 Ae 44 G IV-VI 54 Dwarf Novae 35 Am 45 G I-II 55 Classical Novae 36 Ap 46 else K IV-VI 56 Supernovae 37 WDA 47 K I-III 57 Symbiotic Stars 38 Horizontal Branch 48 M dwarf 58 T Tauri 39 Composite 49 M I-III 59 X-ray OBJECT CLASSES 60 - 79 60 Shell Star 70 Central Star of PN 61 Eta Carinae 71 Planetary Nebula 62 Pulsar 72 H II Region 63 Nova-like 73 Reflection Nebula 64 Stellar objects 74 Dark Cloud (others) (absorption spectrum) 65 misidentified 75 Supernova Remnant 66 Interacting Binaries 76 Ring Nebula 67 77 68 78 69 Herbig - Haro object 79 OBJECT CLASSES 80 - 99 80 Spiral Galaxy 90 Intergalactic Medium 81 Elliptical Galaxy 91 82 Irregular Galaxy 92 83 Globular Cluster 93 84 Seyfert Galaxy 94 85 Quasar 95 86 Radio Galaxy 96 87 BL Lacertae object 97 88 Emission Line Galaxy 98 Wavelength Calibration (non Seyfert) (NASA log) 89 99 NULLS & FLAT fields (NASA log) 25 Search on homogeneous Object IDs
IUE IUE Related (e.g.WAVECAL's) HD Henry Draper BD Bonner Durchmusterung CD Cordova Dutchmusterung CPD Cape Durchmusterung V* Variable Stars (Kukarkin) WD White Dwarfs (Villanova Un.) GD Giglas White Dwarfs NGC New General Catalogue IC Index Catalogue PK Perek-Kohoutek (Plan.Neb.) SK, AZV, LMC, SMC, FD (Magellanic clouds) MRK Markarian QSO Hewitt + Burbidge Quasar
Catalogue MCG Morphol. Cat. of Galaxies ESOBE SO(B) Uppsala Catalogue PG Palomar Green Catabgue ABCG Abell Rich Clusters Z Solar System NOVA Novae SN Supernovae AOO Any Other Objects (AOO) 26 DISPLAY COMMAND
Ref Cam+Image Homogen- R.A. Decl Observ. Exp.T. Ob Usage Code No +Aperture eous Id hh:mmss dd:mmss Date Secs. Cl Dubious 58 LWR10004L HD15164 2:2406 10.2130 24FEB81 600.0 40 59 SWP13426L HD99028 11:2119 10:4815 7MAR81 220.0 40 D 60 LWR10090L HD99028 11:2119 10:4815 7MAR81 55.0 40 D 61 SWP13668L HD118216 13:3234 37:2616 6APR81 1500.0 40 U 62 LWR 5230L BD+39 4926 22:4354 39:5059 2AUG79 420.0 40 40 63 SWP 6044L BD+39 4926 22:4354 39:5059 2AUG79 2400.0 40 40 64 SWP 6512L HD178524 19:0646 -21:0559 14SEP79 1260.0 40 702 65 SWP 6514L HD163506 17:5323 26:0259 14SEP79 1500.0 40 501 66 SWP 7344L HD118216 13:3233 37:2559 8DEC79 2100.0 40 741 67 LWR 6595S HD132322 14:5725 -63:4359 9JAN80 300.0 40 503 68 LWR 6595L HD132322 14:5725 -63:4359 9JAN80 600.0 40 703 69 SWP 7619S HD132322 14:5725 -63:4359 9JAN80 900.0 40 502 60 SWP 7619L HD132322 14:5725 -63:4359 9JAN80 1800.0 40 702 61 SWP 7793S HD 93614 10:4556 2:3900 27JAN80 220.0 40 501 62 SWP 7793L HD 93614 10:4556 2:3900 27JAN80 260.0 40 701 63 LWR 6005L HD 31964 4:5822 43:4500 1NOV79 120.0 40 801 64 SWP 7063S HD 31964 4:5822 43:4500 1NOV79 960.0 40 721 65 SWP 7063L HD 31564 4:5822 43:4500 1NOV79 1200.0 40 821 66 SWP 9375L HD175813 18:5521 -37:1027 26JUN80 3000.0 40 27 SAVE DESCRIPTORS COMMAND
28 SELECT COMMAND
EXAMPLE: Selecting ranges of displayed spectra: 8-14
29 AUXILIARY INFORMATION (Dubious and Usage Data)
30 How to Convert Selected Spectra into a Usable Form
(UNSPL)
A FIGURE IS MISSING HERE
31 RUNNING UNSPL
32 Appendix A: UNSPL Output Format Descriptions
33 ASCII TABLE
34 FITS FORMAT (IUE Extension)
Block 2 of the FITS file contains the spectrum pixels as a string of binary
half words, the number
of pixels being given by the NAXIS 1 keyword in the FITS header.
Block 4 of the FITS file contains the error flags, one per pixel, as a string
of binary half words. The
number of pixels is given by the NAXIS1 keyword in the FITS header.
35 Appendix B: MIDAS FORMAT
36 Appendix C: LOCAL FORMAT