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GCN Circulars

GCN Circulars are rapid astronomical bulletins submitted by and distributed to community members worldwide. They are used to share discoveries, observations, quantitative near-term predictions, requests for follow-up observations, or future observing plans related to high-energy, multi-messenger, and variable or transient astrophysical events. See the documentation for help with subscribing to or submitting Circulars.

Search for Circulars by submitter, subject, or body text (e.g. 'Fermi GRB').
To navigate to a specific circular, enter the associated Circular ID (e.g. 'gcn123', 'Circular 123', or '123').
Advanced Search

To narrow the search results, use advanced search syntax. This allows for specifying which circular field to search (submitter, subject, and/or body). For additional information, refer to the advanced search documentation.

Advanced Search Examples (click to copy):

subject:"Swift"
body:"GRB"
submitter:"Judith Racusin"

20536 results found.

  1. GRB 251013C: MAO/AZT-22 optical observations
  2. GRB 251013C: Swift ToO observations
  3. GRB 251013C: SVOM/COLIBRÍ (FM-GFT) further multi-band optical observations
  4. GRB 251013C: OHP/T193 further optical observations and possible color evolution
  5. GRB 251013C: Calapai Observatory, Massa S. Giorgio (Messina), optical observation
  6. GRB 251014A: PRIME near-infrared upper limits
  7. GRB 251014A: VLT/FORS2 Optical Observation
  8. GRB 251013C: Osservatorio Astronomico "Nastro Verde" optical observations: detection of an bright optical counterpart
  9. GRB 251013C: MarSEC, optical afterglow photometry
  10. GRB 251014B: Swift ToO observations
  11. GRB 251013D: LAST optical upper limit on Swift/BAT-GUANO localization
  12. GRB 251014B: Swift/BAT-GUANO arcminute localization of a short burst
  13. GRB 251013C: Bassano Bresciano Observatory optical observations
  14. GRB 251013C: Early and late-time optical counterpart detection by LCO
  15. LIGO/Virgo/KAGRA S251014cn: NED Galaxies in the 3-Initial Localization Volume
  16. GRB 251013D: Swift ToO observations
  17. GRB 251014A: DDOTI Upper Limit
  18. GRB 251013C NUTTelA-TAO / BSTI Early Measurements
  19. GRB 251013C: ULL-ASTRO-MASTER detection of the optical afterglow with the LCO 40-cm telescope at Sutherland Observatory
  20. GRB 251013C: Asiago optical observations
  21. GRB 251013C: ABObservatory optical observations
  22. GRB 251013C: J band observations by SYSU 80cm infrared telescope
  23. GRB 251011A: Swift/BAT-GUANO arcminute localization of a burst
  24. GRB 251013D: Swift/BAT-GUANO arcminute localization of a burst
  25. GRB 251013C: ALMA detection
  26. GRB 251013C: SVOM/COLIBRÍ (FM-GFT) detection of the optical counterpart
  27. GRB 251013C: DDOTI detection of the optical afterglow
  28. GRB 251013C: SLKT optical afterglow photometry
  29. Swift GRB 251014A: Global MASTER-Net observations report
  30. Fermi trigger No 782044789: Global MASTER-Net observations report
  31. Fermi GRB 251013C: Global MASTER-Net observations report
  32. Fermi GRB 251013B: Global MASTER-Net observations report
  33. Fermi GRB 251013D: Global MASTER-Net observations report
  34. GRB 251013C: Swift-XRT counterpart detection
  35. GRB 251013C: GOTO optical afterglow detection
  36. GRB 251013C: SAO RAS optical observations
  37. GRB 251013C: LCO optical afterglow detection
  38. GRB 251013C: Optical Observations via Virtual Telescope Project, Italy
  39. GRB 251013C: LAST detection of optical counterpart
  40. GRB 251003A: Mondy optical upper limit
  41. Fermi GRB 251013A: Global MASTER-Net observations report
  42. GRB 251011B inspection: MASTER orphan GRB detection
  43. GRB 251011B: Swift/UVOT Upper Limits
  44. Fermi GRB 251011A: Global MASTER-Net observations report
  45. GRB 251011B : MASTER optical observations
  46. GRB 251007B: Swift/UVOT Upper Limits
  47. GRB251007A: Swift/UVOT Detection
  48. GRB 251007B - SVOM/ECLAIRs refined analysis
  49. EP251006a: Global MASTER-Net observations report
  50. GRB 251002A - SVOM/ECLAIRs refined analysis
  51. IceCube Alert 251008A: Global MASTER-Net observations report
  52. EP250911a: Koshka Zeiss-1000 Optical Upper Limit
  53. GRB 251007B: SVOM/VT optical candidate
  54. GRB 251007A: NOT optical observations
  55. GRB 251007A: SVOM/C-GFT optical observations
  56. GRB 251005C: PRIME J-band upper limit
  57. Swift GRB 251007B: Global MASTER-Net observations report
  58. GRB 251007B: SVOM/C-GFT upper limit
  59. Swift GRB 251007A: Global MASTER-Net observations report
  60. GRB 251007B: SVOM detection of a faint burst
  61. GRB 250702B/EP250702a: JWST/NIRCam Observations
  62. GRB 251006A: Swift/BAT-GUANO subthreshold detection of a short burst
  63. GRB 251006B/EP251006a: SVOM/VT optical candidate
  64. Fermi GRB 251006B: Global MASTER-Net observations report
  65. GRB 251005C: COLIBRÍ optical observations
  66. Fermi GRB 251006A: Global MASTER-Net observations report
  67. GRB 251005C: VLT/X-shooter Imaging
  68. GRB 251003A: LAST optical observations
  69. GRB 251002A: LAST optical observations
  70. GRB 251005​C: Swift/UVOT Upper Limits
  71. Swift GRB 251005A: Global MASTER-Net observations report
  72. GRB 251005C: GOTO optical upper limits
  73. Fermi trigger No 781367244: Global MASTER-Net observations report
  74. GRB 251002A: Mondy/AZT-33IK optical observations
  75. EP251003a: Einstein Probe detection of an X-ray transient
  76. GRB 251003A: J-band detection with WINTER
  77. GRB 251002A: NIR observations with WINTER
  78. Fermi GBM Sub-Threshold Detection of GRB 250910A
  79. GRB 251001B: NIR observations with WINTER
  80. GRB 251002A: Calapai Observatory, Massa S. Giorgio (Messina), optical observation.
  81. GRB 251003A: Swift/UVOT Upper Limits
  82. GRB 251002A: Swift/UVOT detection
  83. GRB 251001B: COLIBRÍ further observations and evidence of a multi-wavelength shallow decay
  84. GRB 251003A: COLIBRÍ photometric redshift
  85. GRB 251003A: GOTO detection of the optical counterpart
  86. GRB 251002A: GOTO detection of optical counterpart
  87. EP250821a: iTelescope T-59 possible detection of the optical counterpart
  88. GRB 251003A: GTC/OSIRIS+ spectroscopic redshift z = 4.412
  89. GRB 251003A: Kilonova-Catcher optical afterglow detection
  90. GRB 251002A: Swift-XRT afterglow detection
  91. GRB 251001B: AbAO optical upper limit
  92. GRB 251002A: Kilonova-Catcher optical afterglow detection
  93. GRB 251002A: AbAO optical observations
  94. GRB 251002A: SVOM/COLIBRÍ (FM-GFT) optical observations
  95. GRB 251002A: J band observations by SYSU 80cm infrared telescope
  96. GRB 251002A: OHP/T193 MISTRAL optical afterglow detection
  97. GRB 251002A: VLT/X-shooter spectroscopic redshift z = 2.178
  98. GRB 251003A: LCOGT Optical Detection
  99. GRB 251003A: COLIBRÍ optical detection of the fading afterglow
  100. GRB 251003A: 1.5m OSN afterglow candidate

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