Dear Colleague:

	We are now sending you, by electronic mail, the FORTRAN source code
for Rev 1.2 of ASURV:  Astronomy Survival Analysis.  Survival analysis
is a body of statistical techniques for the analysis of censored data; that
is, datasets where some of the points are known only to be below or above 
some limit.  This situation occurs frequently in observational astronomy 
when some objects surveyed are not detected.  Rev. 1.2 provides the same
statistical techniques as Rev 1.0 and Rev 1.1 did, but with certain flaws 
that were present in Rev 1.0 and Rev 1.1 removed.  Rev 1.0 is a significant 
revision and expansion of Rev 0.0 that was distributed between 1987 and 1991.  
Most of the statistical methods are described in Feigelson and Nelson 
(Astrophys. J. 293, 192, 1985) and Isobe et al. (Astrophys. J. 306, 490,
1986).  Information regarding the code appears in Isobe and Feigelson (Bull. 
Amer. Astr. Soc. 22, 917, 1990) and LaValley et al. (in Astronomical Data 
Analysis Software and Systems, D. Worrall et al. eds., 1992).

	The ASURV package consists of 59 FORTRAN 77 subroutines sent to you 
in six files, asurv1.f-asurv6.f.  In addition, we provide files asurv.doc and
asurv.tex, which give the ASURV Users' Manual in ASCII and LaTeX formats
respectively, and file asurv.etc with subroutine lists, test files and 
Bug Report forms.  These test files correspond to the examples in the 
manual.   To install the package, we suggest removing the mail headers from 
the nine files, printing the manual, and separating the test files from 
asurv.etc for initial testing of the code.  A hard copy of the manual, 
with flow charts useful to those who may wish to modify the code, is 
available upon request.  Then, one should run a FORTRAN compiler and linker 
(e.g. `f77 -o asurv asurv1.f .... asurv6.f' in SunOS), and run the code on 
the test files from asurv.etc.  The output should be checked to ensure 
that it matches the output in the manual.  At this point the user should 
be ready for scientific applications.  

	To ensure that all the files have arrived safely, check that the 
byte lengths match the following list (after removal of the mail headers):

                       file          byte length
                       ----          -----------
                     asurv.etc            9709
                     asurv.tex           74628
                     asurv.doc           71161
                     asurv1.f            62909
                     asurv2.f            64734
                     asurv3.f            61382
                     asurv4.f            62185
                     asurv5.f            60629
                     asurv6.f            58727

Contact us at code@stat.psu.edu (Internet) if any difficulties arise or 
if informal advice regarding use of these methods is needed.  Please be 
sure to send in a Bug Report if any errors are found in the package. 

Good luck!


Michael LaValley (Penn State, Dept. of Statistics)
Takashi Isobe (M.I.T., Center for Space Research)
Eric Feigelson (Penn State, Dept. of Astronomy & Astrophys)


Rev. Jan. 1992
