# The m x1 x2 x3 photometric system

## Basic Reference

Neff J.S., Travis L.D. 1967, Astron. J. 72, 48
## Abstract

Observations of standard stars are presented to define a new intermediate
bandpass photometric system. A comprehensive description of the instrument,
reduction procedures and calibration procedures is given, since some of the
methods are new. Considerable effort was made to remove or reduce all sources
of error in the photometry. Typical mean errors of a single observations in
m(0.55), x1 = m(0.47) - m(0.55), x2 = m(0.37) - m(0.47), and
x3 = m(0.33) - m(0.37) are 10.9, 12, and 13 thousandths of a magnitude,
respectively. A preliminary absolute flux calibration is given, based on
scanner observations of Willstrop and Code. An appendix contains a detailed
treatment of the second-order terms in the absolute calibration and in
atmospheric extinction. This paper is the second in a series on this
photometric system. Additional papers will be concerned with applications
of the system to stellar classification and to the study of the physical
properties of variable stars.

## Content

## Access to the data and references

## Asiago Database on Photometric System (ADPS)

## Indices and Parameters

m, x1, x2, x3

- x1 = m(0.47) - m(0.55)
- x2 = m(0.37) - m(0.47)
- x3 = m(0.33) - m(0.37)
- x4 = x1 + x2 = m(0.37) - m(0.55)
- x5 = x3 + x4 = m(0.33) - m(0.55)
- x6 = x2 + x3 = m(0.33) - m(0.47)

## Filters

**0.33**
- Max transmission : 3350 Å ; Equivalent rectangular bandpass : 343 Å
**0.37**
- Max transmission : 3690 Å ; Equivalent rectangular bandpass : 145 Å
**0.47**
- Max transmission : 4680 Å ; Equivalent rectangular bandpass : 193 Å
**0.55**
- Max transmission : 5450 Å ; Equivalent rectangular bandpass : 217 Å

## Photomultiplier

RCA 1P21

Please, send your
commentsto Jean-Claude.Mermilliod@obs.unige.ch

Jean-Claude.Mermilliod@obs.unige.ch

Last update: 13 September 2002