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GCN Circulars

GCN Circulars are rapid bulletins submitted by and distributed to the community. 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"

20520 results found.

  1. GRB 250103A: 1.6m Mephisto optical observations
  2. GRB 250108A: Swift-XRT afterglow detection
  3. LIGO/Virgo/KAGRA S250108eo: Identification of a GW compact binary merger candidate
  4. GRB 250108B: Swift/UVOT Upper Limits
  5. GRB 250103A: Swift-XRT afterglow detection
  6. GRB 250108B: Enhanced Swift-XRT position
  7. GRB 250108B: Swift detection of a burst
  8. GRB 250107A: Swift/BAT-GUANO arcminute localization of a burst
  9. GRB 250101A: J band upper limit by SYSU 80cm telescope
  10. EPWXT01709129925: Xinglong optical observations
  11. GRB 250106A: NOT optical observations
  12. GRB 250103B: REM optical/NIR upper limits
  13. GRB 250101A: REM optical/NIR counterpart detection
  14. GRB 250106A: Swift-XRT observations
  15. GRB 250103B: Swift-XRT refined Analysis
  16. GRB 250103B: LCO/1m optical afterglow candidate detection
  17. GRB 250103A: Bassano Bresciano Observatory upper limit
  18. GRB 250103B: VLT/X-shooter spectroscopic redshift z = 1.416
  19. GRB 250101A: 1.3m DFOT optical afterglow detection
  20. GRB 241229A: 1.3m DFOT upper limit
  21. GRB 241228B: 1.3m DFOT Optical observations
  22. GRB 241228A: 1.3m DFOT upper limit
  23. LIGO/Virgo/KAGRA S250104v: Identification of a GW compact binary merger candidate
  24. GRB 250103A: Montarrenti Observatory optical detection
  25. GRB 250101A: further LCOGT optical afterglow observations
  26. GRB 250103A: Redshift 4.01 from OSIRIS+/GTC
  27. GRB 250103A: TSHAO optical upper limit
  28. GRB 250103A: Fermi GBM Observation
  29. GRB 250103B: LCOGT Optical Upper Limit
  30. IceCube-250102A: Upper limits from a search for additional neutrino events in IceCube
  31. EP250101a: Liverpool Telescope optical upper limit
  32. IceCube-250101A: Upper limits from a search for additional neutrino events in IceCube
  33. GRB 250101a: Liverpool Telescope optical follow-up
  34. GRB 250103B: Swift detection of a burst
  35. GRB 250103A: Xinglong 2.16m Optical Candidate
  36. GRB 250101B: SVOM/GRM observation
  37. GRB 250103A: GOTO optical upper limit
  38. GRB 250103A: SVOM/C-GFT optical upper limit
  39. GRB 250101A: NUTTelA-TAO / BSTI Optical Limits
  40. EP241231b: optical upper limit with the Liverpool Telescope
  41. GRB 250103A: SVOM detection of a long burst (duplicate submission)
  42. GRB 250103A: SVOM detection of a long burst
  43. EP250101a: Xinglong optical upper limit
  44. GRB 250101A: further SAO RAS optical observations
  45. GRB 250101A: LCO optical counterpart detection
  46. EP241231b and EP250101a: EP-WXT detection of two X-ray transients
  47. GRB 250101A: Swift/UVOT Detection
  48. GRB 250101A: 1.6m Mephisto multi-band optical followup
  49. GRB 250101A: Montarrenti Observatory optical observations and rebrightening
  50. GRB 250101A: LCOGT optical afterglow detection
  51. GRB 250101A: OASDG optical observations
  52. GRB 250101A: BOOTES-4/MET optical afterglow detection
  53. GRB 250101A: AKO Optical Afterglow Detection
  54. GRB 250101A: SAO RAS optical observations
  55. GRB 250101A: Enhanced Swift-XRT position
  56. LIGO/Virgo/KAGRA S250101k: Updated Sky localization and Source Classification
  57. GRB 250101A: SVOM/C-GFT early optical observations
  58. GRB 250101A : GIT optical detection
  59. GRB 250101A: GMG Optical Observation
  60. GRB 250101A: Swift detection of a burst with an optical counterpart
  61. EP241217a: VLA Radio Detection

  62. LIGO/Virgo/KAGRA S241231du: Coverage and upper limit from MAXI/GSC observations
  63. LIGO/Virgo/KAGRA S250101k: Identification of a GW compact binary merger candidate
  64. GRB 241229B: Continued CrAO ZTSh observations
  65. LIGO/Virgo/KAGRA S241231bg: Updated NED Galaxies in the Localization Volume
  66. GRB 241228B: Multiband optical monitoring with 1.6m Mephisto
  67. GRB 241229B: SVOM/GRM observation
  68. LIGO/Virgo/KAGRA S241231bg: Identification of a GW compact binary merger candidate
  69. EP241217A: J band upper limit by SYSU 80cm telescope
  70. LIGO/Virgo/KAGRA S241230ev: Identification of a GW compact binary merger candidate
  71. GRB 241229B: SAO RAS optical upper limit
  72. GRB 241228B: SAO RAS optical observations
  73. IceCube-Cascade 241228A: Upper limits from a search for additional neutrino events in IceCube
  74. EP240702a: 7DT Optical upper limits
  75. GRB 240606B: 7DT Optical upper limits
  76. GRB241229B: UVOT upper limits
  77. GRB 241228B: Swift-XRT afterglow detection
  78. GRB 241228A: Mondy optical afterglow observations
  79. GRB 241229A: GOTO optical upper limits
  80. GRB 241228B: VLT/X-shooter redshift of z = 2.674
  81. GRB 241228A: NOT optical upper limits
  82. GRB 241228B: LCO optical observation
  83. GRB 241228B: Swift/BAT-GUANO localization skymap of a burst
  84. GRB241228B: GROWTH-India Telescope optical observations
  85. GRB 241226A: Swift/BAT-GUANO localization skymap of a burst
  86. GRB 241228A: GROWTH-India telescope optical upper limit
  87. GRB 241228B: TRT optical counterpart confirmation
  88. GRB 241228A: Swift/UVOT Upper Limits
  89. GRB 241228A: Enhanced Swift-XRT position
  90. GRB 241228A: Swift detection of a burst
  91. IceCube-241224A: Upper limits from a search for additional neutrino events in IceCube
  92. EP241223a: Mondy AZT-33IK optical observations
  93. GRB 241029A: LCO optical observation
  94. GRB 241223A: Swift-XRT observations
  95. LIGO/Virgo/KAGRA S241225v: Identification of a GW compact binary merger candidate
  96. GRB 241029A: AbAO AS-32 optical observations
  97. LIGO/Virgo/KAGRA S241225c: Identification of a GW compact binary merger candidate
  98. EP241223a
  99. EP241223a: EP-WXT detection of a fast X-ray transient
  100. GRB241113A: 7DT Optical upper limits

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