- Thank you received: 0
Requiem for Relativity
- Joe Keller
- Offline
- Platinum Member
Less
More
17 years 7 months ago #18913
by Joe Keller
Replied by Joe Keller on topic Reply from
I've looked retrospectively at some of the photos that have been taken. By chance, the presumed coordinates of Frey are included in these, much oftener than those of Barbarossa. I now see four likely detections of Frey. With my numbering system, they are:
Steve Riley's Object #1. April 1, 2007, 07:39 UT.
RA 11 26 24.60 Decl -8 57 48.5.
Though this object is not entirely starlike, and several even less starlike objects occur nearby, its reality is corroborated by its agreement, when teamed with J. Genebriera's Object #1 (Barbarossa), with Barbarossa/Frey Objects A2 & A on the 1954 Palomar plate scan and with Objects B3 & B on the 1986 UK-Australia plate scan. (See above for details.)
Joan Genebriera's Object #2. April 2, 2007, 23:54 UT.
RA 11 26 23.10 Decl -8 57 40.0.
This amounts to a heart-shaped pixel overdensity several arcseconds across. It does not appear on a followup photo taken by Genebriera only a few minutes later.
Robert Turner's Object #1. April 12, 2007, 02:30 UT.
RA 11 26 16.46 Decl -8 56 57.9.
No more impressive than the preceding object, this amounts to a hazy vertical streak parallel to a vertical black streak. Several barely-visible spots of light are nearby. On this photo by Turner through the Bradford Observatory 14" at Tenerife, the nearby star USNO-B 0810-0228763, Red1 & 2 magnitudes +17.6 & +18.1, is moderately easy to see, but another nearby star, with R2 +18.14, is, though starlike in size & shape, moderately difficult even with high magnification. Several nearby stars with magnitudes +18.5 to +19 are more-or-less impossible to see; however, an R2 +19.05 star shows a very faint though starlike exposure pattern.
S. Riley's Object #2. April 24, 2007, 05:41 UT.
RA 11 26 09.58 Decl -8 55 56.0.
This object is starlike except that it is abnormally small. Occasionally catalog stars are likewise small, at this magnitude near the detection limit.
Interpolation between Riley's Objects #1 & #2, linear with quadratic correction terms, shows that Turner's Object #1 is only 5" from expected position. Then the short distances allow plain linear interpolation between Riley's #1 and Turner's #1, which finds that Genebriera's #2 is only 4" from expected.
In all these photos, here near the detection limit, the intensity of stars' exposure patterns varies drastically despite equal catalog magnitude. Also, some stars show abnormal exposure patterns. I think that the positional consistency of these objects, such as they are, warrants the use of larger telescopes to take photos near Frey's predicted position extrapolated from these. This needs to be done soon, because the constellation Crater (S of Leo) is nearing the sun.
Technique for predicting position during the next two weeks:
1. Plot RA vs. time for the four Objects above, on one sheet of graph paper, and Decl vs. time on another sheet.
2. Use a long string to draw a circular arc through the four points on each sheet.
3. Read the RA & Decl off the two graphs.
This should be accurate enough to allow fields of view much smaller than 15'.
If Barbarossa & Frey have more rock & metal than assumed in published models of giant planets, then they will have smaller diameters and fainter magnitudes than predicted by those models. Also, nearby satellites and/or rings would tend to produce aberrant exposure patterns.
Steve Riley's Object #1. April 1, 2007, 07:39 UT.
RA 11 26 24.60 Decl -8 57 48.5.
Though this object is not entirely starlike, and several even less starlike objects occur nearby, its reality is corroborated by its agreement, when teamed with J. Genebriera's Object #1 (Barbarossa), with Barbarossa/Frey Objects A2 & A on the 1954 Palomar plate scan and with Objects B3 & B on the 1986 UK-Australia plate scan. (See above for details.)
Joan Genebriera's Object #2. April 2, 2007, 23:54 UT.
RA 11 26 23.10 Decl -8 57 40.0.
This amounts to a heart-shaped pixel overdensity several arcseconds across. It does not appear on a followup photo taken by Genebriera only a few minutes later.
Robert Turner's Object #1. April 12, 2007, 02:30 UT.
RA 11 26 16.46 Decl -8 56 57.9.
No more impressive than the preceding object, this amounts to a hazy vertical streak parallel to a vertical black streak. Several barely-visible spots of light are nearby. On this photo by Turner through the Bradford Observatory 14" at Tenerife, the nearby star USNO-B 0810-0228763, Red1 & 2 magnitudes +17.6 & +18.1, is moderately easy to see, but another nearby star, with R2 +18.14, is, though starlike in size & shape, moderately difficult even with high magnification. Several nearby stars with magnitudes +18.5 to +19 are more-or-less impossible to see; however, an R2 +19.05 star shows a very faint though starlike exposure pattern.
S. Riley's Object #2. April 24, 2007, 05:41 UT.
RA 11 26 09.58 Decl -8 55 56.0.
This object is starlike except that it is abnormally small. Occasionally catalog stars are likewise small, at this magnitude near the detection limit.
Interpolation between Riley's Objects #1 & #2, linear with quadratic correction terms, shows that Turner's Object #1 is only 5" from expected position. Then the short distances allow plain linear interpolation between Riley's #1 and Turner's #1, which finds that Genebriera's #2 is only 4" from expected.
In all these photos, here near the detection limit, the intensity of stars' exposure patterns varies drastically despite equal catalog magnitude. Also, some stars show abnormal exposure patterns. I think that the positional consistency of these objects, such as they are, warrants the use of larger telescopes to take photos near Frey's predicted position extrapolated from these. This needs to be done soon, because the constellation Crater (S of Leo) is nearing the sun.
Technique for predicting position during the next two weeks:
1. Plot RA vs. time for the four Objects above, on one sheet of graph paper, and Decl vs. time on another sheet.
2. Use a long string to draw a circular arc through the four points on each sheet.
3. Read the RA & Decl off the two graphs.
This should be accurate enough to allow fields of view much smaller than 15'.
If Barbarossa & Frey have more rock & metal than assumed in published models of giant planets, then they will have smaller diameters and fainter magnitudes than predicted by those models. Also, nearby satellites and/or rings would tend to produce aberrant exposure patterns.
Please Log in or Create an account to join the conversation.
17 years 7 months ago #16817
by Stoat
Replied by Stoat on topic Reply from Robert Turner
Looks like it's time to try some begging letters to this guy Faulkes and the Liverpool two metre perhaps. As they say in my part of the world, "shy bairns get nowt!"
Another group that might be worth chasing up on would be the small band of supernova chasers. Amateurs but they tend to have very good kit.
I'd go for the short but sweet approach. I wouldn't mention Frey at all. No more than four or five paragraphs. Where it is, how long you need on the scope, and the offer to send fits files from the smaller telescopes.
The last paragraph would be the hard one to write. It has to suggest that for a small outlay, the results could be astonishing, without being too gushing about it.
Another group that might be worth chasing up on would be the small band of supernova chasers. Amateurs but they tend to have very good kit.
I'd go for the short but sweet approach. I wouldn't mention Frey at all. No more than four or five paragraphs. Where it is, how long you need on the scope, and the offer to send fits files from the smaller telescopes.
The last paragraph would be the hard one to write. It has to suggest that for a small outlay, the results could be astonishing, without being too gushing about it.
Please Log in or Create an account to join the conversation.
- Joe Keller
- Offline
- Platinum Member
Less
More
- Thank you received: 0
17 years 7 months ago #19502
by Joe Keller
Replied by Joe Keller on topic Reply from
<blockquote id="quote"><font size="2" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by Stoat</i>
<br />Looks like it's time to try some begging letters to this guy Faulkes and the Liverpool teo metre perhaps. As they say in my part of the world, "shy bairns get nowt!"
Another group that might be worth chasing up on would be the small band of supernova chasers. Amateurs but they tend to have very good kit.
I'd go for the short but sweet approach. I wouldn't mention Frey at all. No more than four or five paragraphs. Where it is, how long you need on the scope, and the offer to send fits files from the smaller telescopes.
The last paragraph woul be the hard one to write. It has to suggest that for a small outlay, the results could be astonishing, without being too gushing about it.
<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">
Dear "Stoat",
Thanks for the ideas. Yesterday I emailed 21 serious amateurs on a list who had their own observatory domes. I think two small colleges were among them. I discriminated in favor of those with scopes at least 12" and latitudes +35 or below. The largest scope I noticed among them was 24". Several were in the S. hemisphere.
- Joe Keller
<br />Looks like it's time to try some begging letters to this guy Faulkes and the Liverpool teo metre perhaps. As they say in my part of the world, "shy bairns get nowt!"
Another group that might be worth chasing up on would be the small band of supernova chasers. Amateurs but they tend to have very good kit.
I'd go for the short but sweet approach. I wouldn't mention Frey at all. No more than four or five paragraphs. Where it is, how long you need on the scope, and the offer to send fits files from the smaller telescopes.
The last paragraph woul be the hard one to write. It has to suggest that for a small outlay, the results could be astonishing, without being too gushing about it.
<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">
Dear "Stoat",
Thanks for the ideas. Yesterday I emailed 21 serious amateurs on a list who had their own observatory domes. I think two small colleges were among them. I discriminated in favor of those with scopes at least 12" and latitudes +35 or below. The largest scope I noticed among them was 24". Several were in the S. hemisphere.
- Joe Keller
Please Log in or Create an account to join the conversation.
- Joe Keller
- Offline
- Platinum Member
Less
More
- Thank you received: 0
17 years 7 months ago #19701
by Joe Keller
Replied by Joe Keller on topic Reply from
Open letter to the Secretary of the Navy (U. S. A.)
To: the Hon. Donald C. Winter, Ph.D.
Secretary of the Navy
Washington, D. C., USA
From: Joseph C. Keller, M. D.
POB 9122
Ames, Iowa 50014 USA
Date: May 15, 2007
Subject: planetary discovery
Dear Secretary Winter:
Please order someone with a big telescope to look for planets near these coordinates:
RA 11h 26m Decl -8.9 deg (J2000)
At 00:42 on March 25, 2007, UT, amateur astronomer Joan Genebriera of Barcelona, Spain, using a 16” telescope and electronic camera at Tacande Observatory on Tenerife in the Canary Is., aiming her telescope at coordinates I provided, recorded objects near
RA 11 26 22.2 Decl -9 04 59 and
RA 11 26 31.8 Decl -9 00 11
These objects seem to be identical with objects found on the online scan of the1954 (48” Schmidt camera) Palomar sky survey plate “POSS-I Red” at these coordinates:
RA 11 02 25.2 Decl -5 56 11 and
RA 11 03 12.4 Decl -5 58 09
and the scan of the 1986 (also 48” Schmidt) Australian sky survey plate “UK Red” at:
RA 11 16 51.8 Decl -7 49 40 and
RA 11 16 56.1 Decl -7 55 14
Assuming a mass ratio of 0.865: 0.135, and a distance, from the sun, of 197.75 Astronomical Units, the center of gravity seems to be in orbit around the sun. The eccentricity of the orbit is < 0.009 with 90% confidence. (The eccentricity of Neptune’s orbit is 0.009.) Though uncommon, double star orbits of this size and eccentricity are known. Known double stars are observationally biased toward systems of more equal mass.
The apparent period of the orbit equals the period of advancement of the 5:2 Jupiter:Saturn resonance, to the accuracy to which the latter is known. Correction for the eccentricities of Jupiter’s and Saturn’s orbits shows that my newly discovered objects lie, in projection, within a fraction of a degree of one of the five mean Jupiter:Saturn resonance points.
The objects lie only two degrees prograde from the positive Cosmic Microwave Background dipole. The dipole lies on the objects’ orbit to within a fraction of a degree, the accuracy to which the dipole is known. This is consistent with a new, gravitational theory of the CMB, which would revolutionize our understanding of the relationship between gravity and electricity.
For reasonable masses, correction for the tidal gravity of the objects, reduces the variation of the Pioneer Anomalous Acceleration. The net Anomalous Acceleration becomes fairly smoothly decreasing with distance from the sun.
I think that despite the likely 0.01 solar mass for the combined objects, they fail to disrupt the solar system, because small shifts in the orbital planes of the known planets, counter the torque. Depending on composition, the objects might have smaller diameters than predicted by published giant planet theory.
The first photos taken in the search for these objects were by amateur astronomer Robert Turner of England, using the 14” telescope and electronic camera of the Bradford College Observatory, also on Tenerife, Canary Is. Amateur astronomer Steve Riley of California, USA, took many photos using an 11” telescope and electronic camera at Buena Vista Observatory in California. The objects are near the detection limit for all these observers. Known stars of magnitude equal to the objects, often are absent or distorted in the photos. Despite these problems, Turner’s later photos, Genebriera’s, and especially Riley’s, show several alternative or additional detections of the objects.
Sincerely,
Joseph C. Keller, M. D.
To: the Hon. Donald C. Winter, Ph.D.
Secretary of the Navy
Washington, D. C., USA
From: Joseph C. Keller, M. D.
POB 9122
Ames, Iowa 50014 USA
Date: May 15, 2007
Subject: planetary discovery
Dear Secretary Winter:
Please order someone with a big telescope to look for planets near these coordinates:
RA 11h 26m Decl -8.9 deg (J2000)
At 00:42 on March 25, 2007, UT, amateur astronomer Joan Genebriera of Barcelona, Spain, using a 16” telescope and electronic camera at Tacande Observatory on Tenerife in the Canary Is., aiming her telescope at coordinates I provided, recorded objects near
RA 11 26 22.2 Decl -9 04 59 and
RA 11 26 31.8 Decl -9 00 11
These objects seem to be identical with objects found on the online scan of the1954 (48” Schmidt camera) Palomar sky survey plate “POSS-I Red” at these coordinates:
RA 11 02 25.2 Decl -5 56 11 and
RA 11 03 12.4 Decl -5 58 09
and the scan of the 1986 (also 48” Schmidt) Australian sky survey plate “UK Red” at:
RA 11 16 51.8 Decl -7 49 40 and
RA 11 16 56.1 Decl -7 55 14
Assuming a mass ratio of 0.865: 0.135, and a distance, from the sun, of 197.75 Astronomical Units, the center of gravity seems to be in orbit around the sun. The eccentricity of the orbit is < 0.009 with 90% confidence. (The eccentricity of Neptune’s orbit is 0.009.) Though uncommon, double star orbits of this size and eccentricity are known. Known double stars are observationally biased toward systems of more equal mass.
The apparent period of the orbit equals the period of advancement of the 5:2 Jupiter:Saturn resonance, to the accuracy to which the latter is known. Correction for the eccentricities of Jupiter’s and Saturn’s orbits shows that my newly discovered objects lie, in projection, within a fraction of a degree of one of the five mean Jupiter:Saturn resonance points.
The objects lie only two degrees prograde from the positive Cosmic Microwave Background dipole. The dipole lies on the objects’ orbit to within a fraction of a degree, the accuracy to which the dipole is known. This is consistent with a new, gravitational theory of the CMB, which would revolutionize our understanding of the relationship between gravity and electricity.
For reasonable masses, correction for the tidal gravity of the objects, reduces the variation of the Pioneer Anomalous Acceleration. The net Anomalous Acceleration becomes fairly smoothly decreasing with distance from the sun.
I think that despite the likely 0.01 solar mass for the combined objects, they fail to disrupt the solar system, because small shifts in the orbital planes of the known planets, counter the torque. Depending on composition, the objects might have smaller diameters than predicted by published giant planet theory.
The first photos taken in the search for these objects were by amateur astronomer Robert Turner of England, using the 14” telescope and electronic camera of the Bradford College Observatory, also on Tenerife, Canary Is. Amateur astronomer Steve Riley of California, USA, took many photos using an 11” telescope and electronic camera at Buena Vista Observatory in California. The objects are near the detection limit for all these observers. Known stars of magnitude equal to the objects, often are absent or distorted in the photos. Despite these problems, Turner’s later photos, Genebriera’s, and especially Riley’s, show several alternative or additional detections of the objects.
Sincerely,
Joseph C. Keller, M. D.
Please Log in or Create an account to join the conversation.
- Joe Keller
- Offline
- Platinum Member
Less
More
- Thank you received: 0
17 years 7 months ago #19583
by Joe Keller
Replied by Joe Keller on topic Reply from
Barbarossa and Cassini's third law.
Cassini's third law is widely applicable (Colombo, Astronomical Journal, 1966). Using the Barbarossa-Frey center of mass from 1954 and 1986, I found (epoch 2000.0):
ascending node: 283.688 deg ecliptic long.
inclination: 12.162 deg
inclination to mean (angular momentum average) orbital plane of J,S,U,N: 13.75 deg
The tilt of the sun's axis, relative to the planets' orbits, is about 30 deg away from what would be needed, for the sun's equator, the mean (see above) orbital plane of the planets, and Barbarossa's orbital plane, to obey Cassini's third law. The tilt of Saturn's orbit, relative to Jupiter's, also is about 30 degrees away from what would be needed, for Saturn's, Jupiter's and Barbarossa's orbits to obey Cassini's third law: Jupiter's ascending node is 101 deg ecliptic longitude, Saturn's 114, and Barbarossa's descending node 103.7. On the other hand, Cassini's third law applies fairly accurately to the trio of Barbarossa's orbit, Jupiter's orbit, and the mean plane of everyone else's angular momentum combined (basically Saturn + Sun). The five biggest non-Earth planets have ascending nodes ranging from 74 to 132 (Mercury's is 48 and Mars' 50.)
Barbarossa manifests the Tifft period.
"The problem in working with short [redshift] periods...is not measurement, it is physical intuition. ...it seems inconceivable that fluctuations within systems would not mask periodic order on a very small scale. Despite the near universality of this feeling, the data appear to speak otherwise."
- WG Tifft, Astrophysical Journal 468:491+, 1996, p. 506
In the Perseus and Cancer regions (i.e., in much of the sky) Tifft found that galactic redshifts tend to cluster around multiples of 2.8817 km/s. Including a small correction for the masses of the planets, Barbarossa's nearly circular orbital speed is 2.10 km/s. This corresponds to an escape speed, at Barbarossa's distance from the sun, of 2.97 km/s. Maybe binary companions such as Barbarossa tend to form at a distance consistent with Tifft's redshift period. As I've noted elsewhere on Dr. Van Flandern's messageboard, the Tifft periods also manifest themselves within the Milky Way galaxy and within the solar system.
Barbarossa is not a planet; it is a binary companion.
My estimate of Barbarossa's mass, is near the theoretical threshold for transient lithium burning, therefore near the boundary between star and planet, as defined by the presence, at any time, of nuclear fusion. Another definition of planet, could be based on the mechanism of formation. Binary star companions farther than 40 AU, from primaries resembling our sun, show little correlation between their orbital planes and the equatorial planes of the primaries (A. Hale, Astronomical Journal 107:306+, 1994). Barbarossa's orbit is about 14deg out of the principal plane of the solar system and 14+7=21deg out of the sun's equatorial plane ( p = (0.37 radian)^2 / 4 = 0.03 ).
When a lone planet orbits a star in a binary system, "Kozai's integral", (1-eccentricity^2)*(cos(inclination))^2, is invariant (M Holman et al, Nature 386:254+, 1997). For a lone planet with a circular orbit initially inclined < 39 deg ( p = (0.68 radian)^2 / 4 = 0.12 ) to the companion star's orbit, the planet's orbit merely precesses. (If the planet's orbit is initially eccentric, the 39 must be replaced by a somewhat smaller angle.) With an inclination > 39 deg, even an initially circular orbit eventually will oscillate between small and large eccentricity, and correspondingly large and small inclination, keeping Kozai's integral invariant. Barbarossa's low mass and near-circular orbit would lengthen the timescale, but not reduce the size, of this oscillation. It is Barbarossa's rather small inclination to the orbits of the planets, that allows the eccentricities of the planets to remain small.
Cassini's third law is widely applicable (Colombo, Astronomical Journal, 1966). Using the Barbarossa-Frey center of mass from 1954 and 1986, I found (epoch 2000.0):
ascending node: 283.688 deg ecliptic long.
inclination: 12.162 deg
inclination to mean (angular momentum average) orbital plane of J,S,U,N: 13.75 deg
The tilt of the sun's axis, relative to the planets' orbits, is about 30 deg away from what would be needed, for the sun's equator, the mean (see above) orbital plane of the planets, and Barbarossa's orbital plane, to obey Cassini's third law. The tilt of Saturn's orbit, relative to Jupiter's, also is about 30 degrees away from what would be needed, for Saturn's, Jupiter's and Barbarossa's orbits to obey Cassini's third law: Jupiter's ascending node is 101 deg ecliptic longitude, Saturn's 114, and Barbarossa's descending node 103.7. On the other hand, Cassini's third law applies fairly accurately to the trio of Barbarossa's orbit, Jupiter's orbit, and the mean plane of everyone else's angular momentum combined (basically Saturn + Sun). The five biggest non-Earth planets have ascending nodes ranging from 74 to 132 (Mercury's is 48 and Mars' 50.)
Barbarossa manifests the Tifft period.
"The problem in working with short [redshift] periods...is not measurement, it is physical intuition. ...it seems inconceivable that fluctuations within systems would not mask periodic order on a very small scale. Despite the near universality of this feeling, the data appear to speak otherwise."
- WG Tifft, Astrophysical Journal 468:491+, 1996, p. 506
In the Perseus and Cancer regions (i.e., in much of the sky) Tifft found that galactic redshifts tend to cluster around multiples of 2.8817 km/s. Including a small correction for the masses of the planets, Barbarossa's nearly circular orbital speed is 2.10 km/s. This corresponds to an escape speed, at Barbarossa's distance from the sun, of 2.97 km/s. Maybe binary companions such as Barbarossa tend to form at a distance consistent with Tifft's redshift period. As I've noted elsewhere on Dr. Van Flandern's messageboard, the Tifft periods also manifest themselves within the Milky Way galaxy and within the solar system.
Barbarossa is not a planet; it is a binary companion.
My estimate of Barbarossa's mass, is near the theoretical threshold for transient lithium burning, therefore near the boundary between star and planet, as defined by the presence, at any time, of nuclear fusion. Another definition of planet, could be based on the mechanism of formation. Binary star companions farther than 40 AU, from primaries resembling our sun, show little correlation between their orbital planes and the equatorial planes of the primaries (A. Hale, Astronomical Journal 107:306+, 1994). Barbarossa's orbit is about 14deg out of the principal plane of the solar system and 14+7=21deg out of the sun's equatorial plane ( p = (0.37 radian)^2 / 4 = 0.03 ).
When a lone planet orbits a star in a binary system, "Kozai's integral", (1-eccentricity^2)*(cos(inclination))^2, is invariant (M Holman et al, Nature 386:254+, 1997). For a lone planet with a circular orbit initially inclined < 39 deg ( p = (0.68 radian)^2 / 4 = 0.12 ) to the companion star's orbit, the planet's orbit merely precesses. (If the planet's orbit is initially eccentric, the 39 must be replaced by a somewhat smaller angle.) With an inclination > 39 deg, even an initially circular orbit eventually will oscillate between small and large eccentricity, and correspondingly large and small inclination, keeping Kozai's integral invariant. Barbarossa's low mass and near-circular orbit would lengthen the timescale, but not reduce the size, of this oscillation. It is Barbarossa's rather small inclination to the orbits of the planets, that allows the eccentricities of the planets to remain small.
Please Log in or Create an account to join the conversation.
- cosmicsurfer
- Offline
- Platinum Member
Less
More
- Thank you received: 0
17 years 6 months ago #19460
by cosmicsurfer
Replied by cosmicsurfer on topic Reply from John Rickey
Hi Joe,
I agree with your statement from above post:
"...This is consistent with a new, gravitational theory of the CMB, which would revolutionize our understanding of the relationship between gravity and electricity."
Wondering if you have any source documents or links pertaining to this research area?
My own views are a modification of MM theory in that the Graviton/Antigraviton is a charged particle of higher frequency above the speed of light spectrum and is in itself the driving force behind all mass fluctuations as shown in collider experiments revealing three trillion times per second flipping between states of matter and antimatter in sub B Mesons.
Thanks, John
I agree with your statement from above post:
"...This is consistent with a new, gravitational theory of the CMB, which would revolutionize our understanding of the relationship between gravity and electricity."
Wondering if you have any source documents or links pertaining to this research area?
My own views are a modification of MM theory in that the Graviton/Antigraviton is a charged particle of higher frequency above the speed of light spectrum and is in itself the driving force behind all mass fluctuations as shown in collider experiments revealing three trillion times per second flipping between states of matter and antimatter in sub B Mesons.
Thanks, John
Please Log in or Create an account to join the conversation.
Time to create page: 0.680 seconds