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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"

16159 results found.

  1. GRB 110915A: GMG optical upper limit
  2. GRB 110915A: MITSuME Akeno Optical upper limits
  3. GRB 110915A: MASTER-Net early limit
  4. GRB 110905A / X-ray transient MAXI J1836-194: TNT optical observation
  5. GRB 110905A: Potential BAT trigger on MAXI J1836-194
  6. GRB 110903A: Swift/UVOT Upper Limits
  7. GRB 110820A: optical upper limit
  8. GRB 110825A: GMG optical observation
  9. GRB110825A: ROTSE early time optical limit
  10. GRB 110825A: optical afterglow candidate
  11. GRB 110820A: Swift/UVOT Upper Limits
  12. GRB110820A: MITSuME Ishigakijima Optical Upper Limits
  13. GRB 110820A: CrAO optical upper limit
  14. GRB 110820A: MASTER-NET observations
  15. GRB 110818A: Swift/UVOT Upper Limits
  16. GRB 110818A: Optical afterglow and redshift from VLT/X-shooter
  17. GRB 110801A: optical observations at Mt. Terskol observatory
  18. Reprocessed enhanced Swift-XRT positions and GRB products: update
  19. GRB 110808A: VLT/X-shooter spectroscopy
  20. GRB 110808A: Swift detection of a burst with optical counterpart
  21. GRB 110726A: two epochs of SAO RAS optical observations
  22. GRB 110801A: optical observations in CrAO
  23. EVLA observation for Fermi burst GRB 110721A
  24. GRB110731A: MOA optical observations of the steeply fading afterglow
  25. GRB 110801A: SAO RAS optical observations
  26. GRB110801A: MITSuME Ishigakijima Optical Observation at 1 day after the burst
  27. GRB 110801A: MASTER OT observations
  28. GRB110801A: MITSuME Ishigakijima Optical Observation
  29. GRB 110801A: TLS Optical afterglow confirmation
  30. GRB 110801A: Swift detection of a burst with an optical counterpart
  31. GRB 110731A / EVLA upper limits
  32. GRB110731A: MITSuME Ishigakijima Optical Upper Limits
  33. GRB110731A: Swift/UVOT Observations
  34. GRB 110731A: NOT photometry
  35. Fermi-LAT Detection of GRB110731A
  36. GRB 110731A: Swift detection of a burst with an optical counterpart
  37. Sw J1644+57 (GRB 110328A): Continued VLBA Observations
  38. INTEGRAL Weak trigger #6331: GRT Optical Observation
  39. GRB 110726A: optical upper limit in CrAO
  40. GRB 110726A: EVLA observations
  41. GRB 110726A: IAC80 R-band observations
  42. GRB 110726A: ROTSE-III refined analysis, fast decay in early phase
  43. GRB110726A: MITSuME Ishigakijima Optical Observation
  44. GRB 110726A: Liverpool Telescope observations
  45. GRB 110726: ROTSE-III Detection of Optical Counterpart
  46. GRB 110721A: Preliminary Swift/UVOT Upper Limits
  47. GRB 110721A: Gemini-South spectroscopy of the potential optical counterpart
  48. GRB 110721A: potential counterpart candidate
  49. GRB 110709B / EVLA detection of radio counterpart
  50. GRB 110719A: GRT Optical Observation
  51. GRB 110719A: optical limit by "Pi of the Sky"
  52. Swift/UVOT observations of GRB110719A
  53. GRB 110719A: optical upper limit
  54. GRB 110715A optical observations
  55. Swift J1822.3-1606: Transient Magnetar or Be X-ray Binary?
  56. GRB110715A: GROND Detection of the Optical/NIR Afterglow
  57. GRB 110715A: APEX detection of the submm counterpart
  58. GRB110715A: VLT redshift
  59. GRB 110715A: Swift detection of a bright burst with an optical counterpart
  60. GRB 110709B: Additional Gemini observations and deep limits on an optical afterglow
  61. GRB 110709A: Swift/UVOT Upper Limits
  62. GRB 110709B: Swift/UVOT Detection of Possible Optical Flaring
  63. GRB110709A: MITSuME Ishigakijima Optical upper limits
  64. GRB 110709B: Gemini-South optical observations
  65. GRB 110709B: possible quiescent source in DSS
  66. GRB 110709A: MASTER-NET optical observations
  67. GRB 110708A: Liverpool Telescope observations
  68. SGR 1E 1841-045: early optical limit by "Pi of the Sky"
  69. GRB 110625A: Fermi GBM and LAT observations
  70. GRB 110625A: Swift/UVOT Upper Limits
  71. GRB 110625A: GROND detection of a source inside the XRT error circle
  72. GRB 110625A: ROTSE-III Optical Limits
  73. Swift J185003.2-005627: Swift-XRT/UVOT refined analysis
  74. Swift J185003.2-005627: TAROT La Silla observatory optical observations
  75. Swift J185003.2-005627: TAROT Calern observatory optical observations
  76. GRB 110618A: SMARTS optical observations
  77. GRB 110610A: 1.23m CAHA optical observations
  78. GRB 110610A: Swift/UVOT Upper Limits
  79. Swift detection of the X-ray afterglow of GRB 110604A
  80. GRB 110610A: MASTER-NET optical observations
  81. GRB 110530A: optical observations in Mondy observatory
  82. GRB 110530A: optical observations at Mt. Terskol, second epoch
  83. GRB 110530A: Xinglong TNT observation
  84. GRB 110530A: NOT optical observations
  85. GRB110530A: MITSuME Okayama Optical Observation
  86. GRB 110530A: optical observations at Mt. Terskol
  87. GRB 110530A: MASTER OT observations
  88. GRB 110530A: MITSuME Akeno Optical Observation
  89. GRB 110530A: Swift detection of a burst with an optical afterglow
  90. Swift J1644+57/GRB 110328A, Additional HST Observations
  91. GRB 110521A: MASTER prompt optical limit
  92. GRB 110521A: Swift/UVOT Upper Limits
  93. GRB 110520A: NOT optical follow-ups
  94. GRB 110521A - NOT optical observation
  95. GRB 110521A: MASTER synchronous and early optical observations limit
  96. Swift/UVOT observations of GRB110520A
  97. GRB 110520A - NOT optical observation
  98. GRB 110520A: Skynet/DAO optical observations
  99. GRB 110520A: Liverpool Telescope Observations
  100. GRB 110520A: TAROT Calern observatory optical observations

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