Flags

In addition to redshift quality and spectral features, you can tag objects with classification flags and data quality flags. These help categorize the catalog and document issues.

Object Type Flags#

These flags classify the physical nature of the object. Select all that apply.

Little Red Dot#

Compact, red sources that are candidate high-redshift AGN. Characteristics:

• Very red in rest-frame optical (steep red continuum)
• Compact/unresolved in imaging
• May show broad emission lines
• Typically at z > 4

Broad Line#

Objects showing broad emission lines indicative of AGN activity:

• FWHM > 1000 km/s
• Common in Hα, Hβ, MgII, CIV
• Indicates Type 1 AGN / quasar
• May be combined with "Little Red Dot" if both apply

Lyα Emitter (LAE)#

Galaxies identified primarily by Lyman-alpha emission:

• Strong Lyα emission line
• Often asymmetric line profile
• Usually at z > 2
• May show Lyman break

Balmer Break Galaxy (BBG)#

Galaxies with prominent Balmer break:

• Clear 4000 Å / Balmer break
• Indicates intermediate-age stellar population
• Often at z ~ 1-3
• May show Balmer absorption lines

[OIII] Emitter#

Galaxies with strong [OIII] emission:

• Prominent [OIII] 4959, 5007 Å doublet
• High equivalent width
• Common at z ~ 1-3
• Often indicates high ionization / low metallicity

Hα Emitter#

Galaxies with strong Hα emission:

• Prominent Hα 6563 Å emission
• Star-forming indicator
• May show [NII] companions
• Common at z ~ 0.5-2.5 in NIRSpec

Quiescent#

Galaxies with little or no ongoing star formation:

• Red continuum
• Absorption-dominated spectrum
• Strong 4000 Å break
• No or weak emission lines

Dusty#

Galaxies with significant dust content:

• Very red continuum
• May show silicate absorption
• Attenuated UV/optical emission
• Can obscure emission lines

Star#

Stellar contaminants in the sample:

• Point source in imaging
• Stellar absorption features
• No redshift (z = 0)
• Mark as "Impossible" for redshift quality

Data Quality Flags#

These flags document issues with the data that may affect the reliability of the spectrum or redshift.

Chip Gap#

The spectrum falls in a detector chip gap:

• Missing wavelength coverage
• May lose key emission lines
• Check other gratings for coverage
• Note which features are affected

Contamination#

Another source contaminates the spectrum:

• Flux from nearby object in extraction
• Check the 2D spectrum for contamination
• May affect continuum level or add spurious features
• Common in crowded fields

Stuck Closed Shutter#

A MSA shutter failed to open:

• Missing or significantly reduced flux
• Affects slit let positions
• Check for systematic patterns
• May require re-observation

Multiple Sources#

The extraction includes flux from multiple objects:

• More than one source in the slit
• Blended spectra
• Redshift may be ambiguous
• Check imaging for source positions

No Detection#

No significant flux detected:

• Object not detected in spectrum
• Very faint or outside slit
• Mark as "Impossible" for redshift
• Check acquisition imaging

Low S/N#

Signal-to-noise ratio is insufficient for reliable analysis:

• Features near noise level
• High uncertainty on measurements
• Consider downgrading redshift quality
• May improve with different binning

Spectral Overlap#

Spectra from adjacent slitlets overlap:

• Common in crowded MSA configurations
• Can cause confusion in feature identification
• Check 2D spectrum for overlap
• May affect wavelength calibration

PRISM Corrupted#

Data quality issues specific to PRISM spectrum:

• Bad pixels, artifacts, or reduction issues
• May not affect grating spectra
• Document the nature of the problem
• Check if other gratings are usable

Grating Corrupted#

Data quality issues in one or more grating spectra:

• Bad pixels, artifacts, or reduction issues
• May not affect PRISM
• Specify which grating in comments
• Check other gratings for alternative

Best Practices#

1. Be thorough - Flag all relevant issues, not just the most obvious
2. Check the 2D spectrum - Many issues are clearer in 2D
3. Use comments - Explain unusual or ambiguous situations
4. Consider impact - Does this flag affect redshift reliability?
5. Update as needed - Return to add flags if you notice issues later

Combining Quality and Flags#

Data quality flags should influence your redshift quality rating:

Remember: flags document what you observed; quality reflects your confidence in the redshift.